MATTER-5610 : Extension version update automation

[Sarthak-Shaha]

Issue Link:
MATTER-5610

Description of Problem/Feature:
Create a version update workflow

Description of Fix/Solution:

1. Added Version Update workflow (manual workflow_dispatch) that:

• Accepts inputs for Matter Extension version, SDK version, and whether to update README links.
• Checks out the repo, sets up Python, and runs slc/script/update_version.py with the provided inputs.
• Uses a GitHub App token to create a PR from automation/version_update back to the branch the workflow was run on (so checks trigger properly).

2. Enhanced slc/script/update_version.py to:

• Validate input formats for extension, SDK, and readme flag.
• Update version references in slc/**/*.md and the root README.md.

Testing Done:
Test PR: #435 ( Description is updated )

Follow-up PR will be done in release_2.8 so we can use it to update pointers to 2.8.1