fix(sam): "failed to process" template URI containing ${workspaceFolder}

Problem:
Logs show "failed to process" when initializing the "template registry":

    CloudFormationTemplateRegistry: failed to process: file:///Volumes/workplace/sam-samples/%24%7BworkspaceFolder%7D/lambda-python3.11/template.yaml

Solution:
Replace the special vscode `${workspaceFolder}` variable just-in-time.

P.S.: This is a hack, it should be done earlier in the codepath.
Related comment: https://github.com/aws/aws-toolkit-vscode/blob/a4a184c7031341dae04b2d10d645f464080dbebf/src/lambda/vue/configEditor/samInvokeBackend.ts#L331-L335

Followup to: 616835a

Author: justinmk3

src/lambda/commands/createNewSamApp.ts

@@ -32,7 +32,7 @@ import { addFolderToWorkspace, tryGetAbsolutePath } from '../../shared/utilities
 import { goRuntimes } from '../models/samLambdaRuntime'
 import { eventBridgeStarterAppTemplate } from '../models/samTemplates'
 import { CreateNewSamAppWizard, CreateNewSamAppWizardForm } from '../wizards/samInitWizard'
-import { LaunchConfiguration } from '../../shared/debug/launchConfiguration'
+import { LaunchConfiguration, replaceVscodeVars } from '../../shared/debug/launchConfiguration'
 import { SamDebugConfigProvider } from '../../shared/sam/debugger/awsSamDebugger'
 import { ExtContext } from '../../shared/extensions'
 import { isTemplateTargetProperties } from '../../shared/sam/debugger/awsSamDebugConfiguration'
@@ -395,8 +395,7 @@ export async function addInitialLaunchConfiguration(
         const targetDir: string = path.dirname(targetUri.fsPath)
         const filtered = configurations.filter(config => {
             let templatePath: string = (config.invokeTarget as TemplateTargetProperties).templatePath
-            // TODO: write utility function that does this for other variables too
-            templatePath = templatePath.replace('${workspaceFolder}', folder.uri.fsPath)
+            templatePath = replaceVscodeVars(templatePath, folder.uri.fsPath)
 
             return (
                 isTemplateTargetProperties(config.invokeTarget) &&

src/shared/debug/launchConfiguration.ts

@@ -204,3 +204,13 @@ export async function getReferencedHandlerPaths(launchConfig: LaunchConfiguratio
         .thru(array => new Set(array))
         .value()
 }
+
+/**
+ * Replaces magic vscode variables in a launch config value.
+ */
+export function replaceVscodeVars(val: string, workspaceFolder?: string): string {
+    if (!workspaceFolder) {
+        return val
+    }
+    return val.replace('${workspaceFolder}', workspaceFolder)
+}

src/shared/sam/debugger/awsSamDebugConfigurationValidator.ts

@@ -20,6 +20,7 @@ import {
 } from './awsSamDebugConfiguration'
 import { tryGetAbsolutePath } from '../../utilities/workspaceUtils'
 import { CloudFormationTemplateRegistry } from '../../fs/templateRegistry'
+import { replaceVscodeVars } from '../../debug/launchConfiguration'
 
 export interface ValidationResult {
     isValid: boolean
@@ -69,8 +70,13 @@ export class DefaultAwsSamDebugConfigurationValidator implements AwsSamDebugConf
         ) {
             let cfnTemplate: CloudFormation.Template | undefined
             if (config.invokeTarget.templatePath) {
-                const fullpath = tryGetAbsolutePath(this.workspaceFolder, config.invokeTarget.templatePath)
+                // TODO: why wasn't ${workspaceFolder} resolved before now?
+                const resolvedPath = replaceVscodeVars(
+                    config.invokeTarget.templatePath,
+                    this.workspaceFolder?.uri.fsPath
+                )
                 // Normalize to absolute path for use in the runner.
+                const fullpath = tryGetAbsolutePath(this.workspaceFolder, resolvedPath)
                 config.invokeTarget.templatePath = fullpath
                 // Forcefully add to the registry in case the registry scan somehow missed the file. #2614
                 // If the user (launch config) gave an explicit path we should always "find" it.