git-artifacts(ARM64): add git-credential-manager-core-wrapper

[dennisameling]

In git-for-windows/git#3076, we added a workaround for GCM Core by adding a wrapper in arm64/bin/git-credential-manager-core. What I didn't realize back then was that I had a hard link to GCM Core in my ~/.gitconfig, so everything seemed to work as expected.

However, I just tried a clean installation of Git for Windows on ARM64 and removed my ~/.gitconfig. Then ran into:

PS C:\repos\demo-repo> git push
git: 'credential-manager-core' is not a git command. See 'git --help'.
Username for 'https://github.com':

... even though arm64/bin/git-credential-manager-core was present. When I moved the file to mingw32/bin/git-credential-manager-core, everything started to work as expected:

PS C:\repos\demo-repo> git push
Everything up-to-date

This PR adds git-credential-manager-core to the proper folder in mingw32. Additional benefit is that folks will have this fix included, even when their artifacts weren't built with GitHub Actions:

https://github.com/dennisameling/git/blob/6686bba2f0a38f78f8406116c5adc8e7dcd0fd82/.github/workflows/git-artifacts.yml#L421-L427

I'll remove the workaround in git-artifacts.yml as this PR is a successor to it.

[dennisameling]

Closing in favor of git-for-windows/git#3085