Add automation to create PR for submodule updates

[AaronCrawfis]

Today if any submodule repos (python-sdk, dotnet-sdk, etc.) merge new docs changes, the docs.dapr.io website doesn't reflect the change until the submodule is updated in the docs repo.

Upon each merge to the daprdocs directory within each SDK repo, run a workflow to PR a submodule update within the docs repo. This PR then can be reviewed and merged by the maintainers.

[greenie-msft]

@AaronCrawfis, do you think you can still address this? I'm happy to take ownership if not.

[AaronCrawfis]

@AaronCrawfis, do you think you can still address this? I'm happy to take ownership if not.

That would be awesome if you could take a look! I made it this far when testing, was getting close to getting a working PoC: https://github.com/AaronCrawfis/test1/blob/main/.github/workflows/main.yml

I got to the part where I need a bot with access to the repo to create the PR.

[hhunter-ms]

@AaronCrawfis friendly bump? is this a lost cause?