Feature/ppcvletoolchain

[paulnoalhyt]

• [x] I have reviewed the OFRAK contributor guide and attest that this pull request is in accordance with it.

One sentence summary of this PR (This should go in the CHANGELOG!) Support for PPC VLE in patchmaker and Ghidra.

Link to Related Issue(s) https://github.com/redballoonsecurity/ofrak/issues/238

Please describe the changes in your request. This pull request's goal is to add support for PPC VLE in different OFRAK components:

• definition of the VLE sub-isa
• Installation of the toolchain in the patchmaker Dockerfile. Support of this toolchain in the patchmaker and automated tests for it
• Support for VLE analysis in Ghidra and fixups in the instruction unpacker

Anyone you think should look at this, specifically? @rbs-jacob

[rbs-jacob]

Instead of #341 for allowing secrets (which may or may not work), maybe we can just mark the PPC VLE stuff with # pragma: no cover and not be blocked on that?

Test coverage is all well and good, but I don't know how much we want to block on it for this. There will still be test coverage after merge on the master branch (where secrets will work), just not on PR branches from external contributor forks.