fix: enable --experimental_editions in protoc

When protoc compiles proto files that use the experimental
Editions feature (like google/showcase/v1beta1/testing.proto),
it throws a fatal error unless the --experimental_editions flag
is explicitly passed.

This commit updates the generator to always pass this flag to protoc,
ensuring it doesn't crash when encountering these newer proto files
now that we are relying on the system protoc (v25+).

Author: GautamSharda

core/generator/gapic-generator-typescript/typescript/src/gapic-generator-typescript.ts

@@ -201,6 +201,7 @@ async function main(processArgv: string[]) {
   const protocCommand = [
     `--plugin=protoc-gen-typescript_gapic=${protocPlugin}`,
     `--typescript_gapic_out=${outputDir}`,
+    `--experimental_editions`,
   ];
   if (gapicValidatorOut && validation === 'true') {
     protocCommand.push(`--gapic-validator_out=${gapicValidatorOut}`);