Add issue bot automation to the samples repo

[brooke-hamilton]

Overview of feature request

Add the ability to perform automation actions in issue comments, especially /assign. Currently, the /assign action is only available in the radius repo.

Acceptance criteria

• A commenter can reply to an issue in this repo using the /assign command.
• There is an established pattern for enabling the /assign command in other repos.
• The pattern allows additional commands to be added.
• The pattern allows commands to be enabled in any repo under radius-project with minimal configuration.
• Additional issues are created to enable /assign in other public repos under radius-project where appropriate.

Additional context

The /assign command is enabled in these files in the radius-project/radius repository:

• .github/workflows/radius-bot.yaml
• .github/scripts/radius-bot.js

We need a way to enable the same automation in all radius-project repos without copy/pasting these files to all repos.

AB#12906

[azure-boards]

✅ Successfully linked to Azure Boards work item(s):

• GitHub Issue 12906

[kachawla]

/assign

[kachawla]

/assign @kachawla

[kachawla]

Added in #1746, and just tested on this issue (see above).