Pass template name to README for templates that inherit from 'default' (#3893)

## Changes
The default, default-python, pydabs, and lakeflow-pipelines templates
now correctly display their template name in the generated README
instead of always saying 'default template'.

## Why
Showing the actual template name to customers seems helpful, even if it
comes at the cost of a bit of extra code in the template.

## Tests
Standard template acceptance tests

Author: lennartkats-db

acceptance/bundle/templates/default-python/classic/output/my_default_python/README.md

@@ -1,6 +1,6 @@
 # my_default_python
 
-The 'my_default_python' project was generated by using the default template.
+The 'my_default_python' project was generated by using the default-python template.
 
 * `src/`: Python source code for this project.
   * `src/my_default_python/`: Shared Python code that can be used by jobs and pipelines.

acceptance/bundle/templates/default-python/serverless/output/my_default_python/README.md

@@ -1,6 +1,6 @@
 # my_default_python
 
-The 'my_default_python' project was generated by using the default template.
+The 'my_default_python' project was generated by using the default-python template.
 
 * `src/`: Python source code for this project.
   * `src/my_default_python/`: Shared Python code that can be used by jobs and pipelines.

acceptance/bundle/templates/lakeflow-pipelines/python/output/my_lakeflow_pipelines/README.md

@@ -1,6 +1,6 @@
 # my_lakeflow_pipelines
 
-The 'my_lakeflow_pipelines' project was generated by using the default template.
+The 'my_lakeflow_pipelines' project was generated by using the lakeflow-pipelines template.
 
 * `src/`: Python source code for this project.
 * `resources/`:  Resource configurations (jobs, pipelines, etc.)

acceptance/bundle/templates/lakeflow-pipelines/sql/output/my_lakeflow_pipelines/README.md

@@ -1,6 +1,6 @@
 # my_lakeflow_pipelines
 
-The 'my_lakeflow_pipelines' project was generated by using the default template.
+The 'my_lakeflow_pipelines' project was generated by using the lakeflow-pipelines template.
 
 * `src/`: SQL source code for this project.
 * `resources/`:  Resource configurations (jobs, pipelines, etc.)

libs/template/templates/default-python/databricks_template_schema.json

@@ -2,6 +2,14 @@
     "template_dir": "../default",
     "welcome_message": "Welcome to the default Python template for Databricks Asset Bundles!\n\nAnswer the following questions to customize your project.\nYou can always change your configuration in the databricks.yml file later.\n\nNote that {{workspace_host}} is used for initialization.\n(For information on how to change your profile, see https://docs.databricks.com/dev-tools/cli/profiles.html.)",
     "properties": {
+        "template_name": {
+            "//": "This property is always set to 'default-python'",
+            "skip_prompt_if": {},
+            "type": "string",
+            "default": "default-python",
+            "description": "Template name for documentation",
+            "order": 0
+        },
         "project_name": {
             "type": "string",
             "default": "my_project",

libs/template/templates/default/template/{{.project_name}}/README.md.tmpl

@@ -4,7 +4,7 @@
 {{- $has_python_package_dir := and (or (eq .include_python "yes") (eq .include_job "yes") (eq .include_pipeline "yes")) (not (eq .lakeflow_only "yes"))}}
 {{- $is_lakeflow := eq .lakeflow_only "yes"}}
 
-The '{{.project_name}}' project was generated by using the default template.
+The '{{.project_name}}' project was generated by using the {{.template_name}} template.
 
 * `src/`: {{if eq .language "sql"}}SQL{{else}}Python{{end}} source code for this project.
 {{- if $has_python_package_dir}}

libs/template/templates/lakeflow-pipelines/databricks_template_schema.json

@@ -2,6 +2,14 @@
     "template_dir": "../default",
     "welcome_message": "Welcome to the template for Lakeflow Declarative Pipelines!\n\nPlease answer the below to tailor your project to your preferences.\nYou can always change your mind and change your configuration in the databricks.yml file later.\n\nNote that {{workspace_host}} is used for initialization\n(see https://docs.databricks.com/dev-tools/cli/profiles.html for how to change your profile).",
     "properties": {
+        "template_name": {
+            "//": "This property is always set to 'lakeflow-pipelines'",
+            "skip_prompt_if": {},
+            "type": "string",
+            "default": "lakeflow-pipelines",
+            "description": "Template name for documentation",
+            "order": -1
+        },
         "lakeflow_only": {
             "//": "This property is set by default to adjust this template for Lakeflow Pipelines",
             "skip_prompt_if": {},

libs/template/templates/pydabs/databricks_template_schema.json

@@ -2,6 +2,14 @@
     "template_dir": "../default",
     "welcome_message": "Welcome to PyDABs template for Databricks Asset Bundles!\n\nAnswer the following questions to customize your project.\nYou can always change your configuration in the databricks.yml file later.\n\nNote that {{workspace_host}} is used for initialization.\n(For information on how to change your profile, see https://docs.databricks.com/dev-tools/cli/profiles.html.)",
     "properties": {
+        "template_name": {
+            "//": "This property is always set to 'pydabs'",
+            "skip_prompt_if": {},
+            "type": "string",
+            "default": "pydabs",
+            "description": "Template name for documentation",
+            "order": 0
+        },
         "project_name": {
             "type": "string",
             "default": "my_project",