test: fix ts api guardian and public guard tests on windows (#30105)

This change addresses several issues with ts-api-guardian and public api guards related tests in Windows

The fixes contain 3 main changes:
1) In `stripExportPattern` - replace `^` with `^^^^`  in RegExp due to a double escaping requirment under Windows. Note that under Linux this the extra character has no effect because it's still a valid RegExp in Js.

2. Force `*.patch` files to always be with a LF line sequence instead of CRLF in windows

3. When adding JSDoc comments consider the presence of a carriage return in a line new feed

Partially addresses #29785

PR Close #30105

.gitattributes

@@ -5,5 +5,8 @@
 *.js eol=lf
 *.ts eol=lf
 
+# API guardian patch must always use LF for tests to work
+*.patch eol=lf
+
 # Must keep Windows line ending to be parsed correctly
 scripts/windows/packages.txt eol=crlf

tools/ts-api-guardian/index.bzl

@@ -51,7 +51,8 @@ def ts_api_guardian_test(
     ]
 
     for i in strip_export_pattern:
-        args += ["--stripExportPattern", i]
+        # The below replacement is needed because under Windows '^' needs to be escaped twice
+        args += ["--stripExportPattern", i.replace("^", "^^^^")]
 
     for i in allow_module_identifiers:
         args += ["--allowModuleIdentifiers", i]

tools/ts-api-guardian/lib/serializer.ts

@@ -298,7 +298,7 @@ class ResolvedDeclarationEmitter {
         const jsdocComment = this.processJsDocTags(node, tagOptions);
         if (jsdocComment) {
           // Add the annotation after the leading whitespace
-          output = output.replace(/^(\n\s*)/, `$1${jsdocComment} `);
+          output = output.replace(/^(\r?\n\s*)/, `$1${jsdocComment} `);
         }
       }