add macos codesigning of opm binary for apple silicon

[grokspawn]

Due to apple's requirement that all apple silicon apps must be signed, the app make targets here will not be able to be executed unless they are signed in macos sequoia and later.

For example, if this generates the opm binary at $HOME/devel/operator-registry/bin/opm and we invoke it, without being signed the result will be Killed: 9 messages for each attempted invocation of the compiled unsigned app, for e.g.:

╰$ ./bin/opm --help
[1]    14243 killed     ./bin/opm --help

This is a completely naive approach to rectifying this, and we probably need some more thought on the subject, but this approach at least lets me execute locally-built binaries to examine catalog content.

Description of the change:

Motivation for the change:

Reviewer Checklist

• Implementation matches the proposed design, or proposal is updated to match implementation
• Sufficient unit test coverage
• Sufficient end-to-end test coverage
• Docs updated or added to /docs
• Commit messages sensible and descriptive

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[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 46.80%. Comparing base (dc23843) to head (f2b1a80).
Report is 10 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #1491      +/-   ##
==========================================
- Coverage   48.61%   46.80%   -1.81%     
==========================================
  Files         135      135              
  Lines       12793    15760    +2967     
==========================================
+ Hits         6219     7377    +1158     
- Misses       5533     7342    +1809     
  Partials     1041     1041              

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[tmshort]

This will also hit Raspberry Pi, and miss those older Intel models that can run Sequoia. Did you want to check explicitly for macOS?

Suggested change

	ifeq ($(shell go env GOARCH),arm64)
	ifeq ($(shell go env GOOS),darwin)

[grokspawn]

I didn't want to test GOOS, because intel-based darwin doesn't have this requirement. I couldn't figure out how to do a double conditional well to select only the darwin+arm64 set of targets.