[Fix] Tables with struct subcolumns which have dot in their name are redeployed on databricks_sql_table resource #3866 (#4001)

## Changes
<!-- Summary of your changes that are easy to understand -->

Backticks are removed from the column type in order for struct subfield
names to be compatible with the subfield names deployed. These subfields
names are part of the column type. Example struct<\`x.z\`:string> ==
struct\<x.z:string>

## Tests
<!-- 
How is this tested? Please see the checklist below and also describe any
other relevant tests
-->

- [x] `make test` run locally
- [x] relevant acceptance tests are passing
- [x] using Go SDK

tested using internal integration tests where tables were created and
terraform plans were reviewed to have no changes.

---------

Co-authored-by: Vuong <[email protected]>
Co-authored-by: vuong-nguyen <[email protected]>
Co-authored-by: Tanmay Rustagi <[email protected]>
Co-authored-by: Alex Ott <[email protected]>

Author: 4 people

NEXT_CHANGELOG.md

@@ -8,6 +8,7 @@
 
 ### New Features and Improvements
 
+* Don't redeploy `databricks_sql_table` for tables with struct subcolumns ([#4001](https://github.com/databricks/terraform-provider-databricks/pull/4001)).
 * Added ability to add `comment` when defining a new `databricks_share` ([#4802](https://github.com/databricks/terraform-provider-databricks/pull/4802))
 * Added output attribute `endpoint_url` in `databricks_model_serving` ([#4877](https://github.com/databricks/terraform-provider-databricks/pull/4877)).
 * Deprecate `egg` library type in `databricks_cluster`, `databricks_job`, and `databricks_library` ([#4881](https://github.com/databricks/terraform-provider-databricks/pull/4881)).

catalog/resource_sql_table.go

@@ -562,7 +562,10 @@ var columnTypeAliases = map[string]string{
 }
 
 func getColumnType(columnType string) string {
-	caseInsensitiveColumnType := strings.ToLower(columnType)
+	// client side normalization is necessary to match normalization
+	// that is happening on the backend side
+	columnTypeNoBackticks := strings.ReplaceAll(columnType, "`", "")
+	caseInsensitiveColumnType := strings.ToLower(columnTypeNoBackticks)
 	if alias, ok := columnTypeAliases[caseInsensitiveColumnType]; ok {
 		return alias
 	}