Configure Github source code repository mapping without giving source-code access

### Problem Statement

## Problem

We cannot setup [Sentry stack-trace source-code linking](https://docs.sentry.io/product/integrations/source-code-mgmt/github/#stack-trace-linking) without giving full access to our source-code. But technically this shouldn't be required.

The reason for not giving you full source-code access, is that if you get hacked (like Solarwinds or Heroku), we don't want the hacker to extract our source-code.

This works great with the Sentry CLI, which we are using in Github actions. But for source-code mapping, your system won't allow me to only fill in base-url to the repo and branch name, it requires the app to have access (even though that's not strictly required).

## Bugsnag

Bugsnag offer this without giving them access to source code.


With Bugsnag, we'd set this using their CLI tool, which is one option. Another one would be to set it in the Sentry web UI somewhere.

https://docs.bugsnag.com/build-integrations/bugsnag-cli/create-build/#repository-repository

## UI that I wish would change


### Solution Brainstorm

_No response_

### Product Area

Settings - Repositories