Branch merge reusable workflow

[f-alizada]

Design

https://github.com/dotnet/dnceng/blob/main/Documentation/OnePagers/github-action-inter-branch-merge.md

Changes made

Introduce the reusable github workflow, which could be used for branch merging actions equal to the action "github-dnceng-branch-merge-pr-generator" from https://github.com/dotnet/versions/blob/main/Maestro/subscriptions.json file.

The workflow usese already implemented ps1 script: https://github.com/dotnet/arcade/blob/main/scripts/GitHubMergeBranches.ps1 The file was modified and copied to the .github/workflows/scripts folder. The modifications:

• Fork functionality is removed.

Example of runs

• PR: https://github.com/f-alizada/sdk/pull/19
• Action runs: https://github.com/f-alizada/sdk/actions

[mmitche]

Let me know when you want me to merge this.

[f-alizada]

Let me know when you want me to merge this.

Thank you for the review Let me answer/address the PR review comments and will merge it. After I will run first tests with MSBuild after merge and continue with steps noted.