feat: Support codesigning macOS executables in bun build --compile

[Pranav2612000]

What does this PR do?

Based off #15525, this PR adds support for code signing macos executables. This is done with 2 changes:

1. Support codesigning macOS executables in bun build --compile
2. Deletes the hack where we read the last 4096 bytes of the currently running executables itself to see if it ends with "-- Bun --\n" . We now add a __BUN,__bun section in the macho executable so all we need to do is a single pointer lookup to find out if the current executable is a standalone executable and to get the data. This will also reduce memory usage because we no longer need to do another memory allocation to read through the standalone executable's code.

How did you verify your code works?

• Ensured that bun is able to generate binaries which are codesignable.

Fixes #7208

[Jarred-Sumner]

Wow nice find. The state of the Linux version of this was not ready - it had similar off-by-one issues somewhere - so we can't fully delete the original code.

[Pranav2612000]

Wow nice find. The state of the Linux version of this was not ready - it had similar off-by-one issues somewhere - so we can't fully delete the original code.

Oops. Do you have plans to look at this? If not, I can give the linux one a try as well. I'm guessing that Linux doesn't have concept of CodeSigning so the issue is that the output file is not executing correctly. Is that right?

Can we keep the older linux version?

[Jarred-Sumner]

Judging by the tests it looks like there's some more work to do on the macOS parts before this can move forward

If you want to take the Linux one feel free but I suggest doing this one step at a time to make sure it ships

[Pranav2612000]

Makes sense @Jarred-Sumner !
I'm working on getting the Mac version working first.
How flaky are the tests in general? Asking because the same tests are passing locally.
I'm able to reproduce it now. Any tips on how to debug and fix this.

I can see that the errors are probably due to storage full errors. I tested out both production and debugs builds and both have the same size ~50MB ( ~350MB for debug ) for simple hello-world