Replace check-for-release steps written in Python with custom Gradle tasks

[myhau]

First explore if this is viable and would indeed be better.

Related:

• https://github.com/VirtuslabRnD/pulumi-kotlin/pull/258/files#diff-8472ec0c6bff955f7305fd0db3721418acd123179e2b285689f471b71b5f3940R58-R62
• Disable attempts to publish snapshots to Maven Central #258 (comment)

• pulumi-kotlin/.github/workflows/publish_to_maven_local.yml

  Lines 39 to 50 in 089560e

  	- name: Check if publication to Maven Local is necessary
  	id: check-for-release
  	shell: python
  	run: |
  	import os
  	import json
  	with open("src/main/resources/version-config.json") as version_config:
  	schemas = json.load(version_config)
  	version = [schema["kotlinVersion"] for schema in schemas if schema["providerName"] == "${{ matrix.provider }}"][0]
  	is_release = not version.endswith("-SNAPSHOT")
  	with open(os.environ['GITHUB_OUTPUT'], 'a') as fh:
  	fh.write('is_release=' + str(is_release).lower())