Avoid git-switch for better backwards compatibility

[whoisninjaturtle]

Replace git-switch commands with git-checkout equivalents for git < 2.23 compatibility

[MGatner]

I had to go read up on the different orphan commands!

If you want to start a disconnected history... then you should clear the index and the working tree right after creating the orphan branch by running git rm -rf . from the top level of the working tree.

Looks good! Is this what you have been using? It works for you?

[whoisninjaturtle]

I configured a test machine with git > 2.23/Composer 2 and stepped through the original patch line-by-line while investigating the resulting branches. On a second machine, with git < 2.23 and Composer 1, I ran through the same process with my modified version of patch to compare the two workflows. As far as I can tell the only difference is that creating the orphan with switch automatically clears the working tree, while checkout does not.

I had to read up on it a little bit as well. To the best of my understanding, the switch command does not actually add any new functionality, at least not for our purposes here; it is simply a reorganization of existing functionality to improve naming and sometimes, like in the case of orphan branches here, add a little sugar behind the scenes that wasn't there before.

FWIW I use CI4 for work and I've already used this modified version of patch to start updating Production-level streams, so I feel fairly confident it's still doing what it should be.

[MGatner]

My guy/gal! Thank you for your thoroughness: I am very happy to support this.