fix: make proto-check-breaking work for forks

[JimLarson]

Description

The make proto-check-breaking always checks for incompatible proto changes against the master branch of cosmos/cosmos-sdk, regardless of whether the PR in question is on a fork or release branch.

Changes the workflow to dynamically specify the target repository and branch of the PR, and changes the Makefile to accept these parameters. Outside of CI testing, can specify the parameters on the make command line.

Probably closes cosmos#8907

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Author Checklist

I have...

• included the correct type prefix in the PR title
• added ! to the type prefix if API or client breaking change
• targeted the correct branch (see PR Targeting)
• provided a link to the relevant issue or specification
• followed the guidelines for building modules
• included the necessary unit and integration tests
• added a changelog entry to CHANGELOG.md
• included comments for documenting Go code
• updated the relevant documentation or specification
• reviewed "Files changed" and left comments if necessary
• confirmed all CI checks have passed

Reviewers Checklist

All items are required. Please add a note if the item is not applicable and please add
your handle next to the items reviewed if you only reviewed selected items.

I have...

• confirmed the correct type prefix in the PR title
• confirmed ! in the type prefix if API or client breaking change
• confirmed all author checklist items have been addressed
• reviewed state machine logic
• reviewed API design and naming
• reviewed documentation is accurate
• reviewed tests and test coverage
• manually tested (if applicable)

[michaelfig]

Well done!