[WIP] Add debug bytecode

[jmid]

Motivated by recent crashes in bytecode:

• #412
• #440
• #446

this WIP PR adds bytecode debug workflows for Linux, macOS, and MinGW.

[jmid]

Rebased and updated

• to reflect the macOS ARM64 vs Intel workflow split
• to add scheduled runs on these new workflows

[jmid]

Rebased and updated

• to reflect the new GitHub actions setup and
• adding a 5.4.0 workflow too

This is now limited to just Linux bytecode debug. We have seen mostly runtime assertion failures recently, so it should be helpful to catch these under the bytecode interpreter too.

[jmid]

Note to self: Like the native debug workflows, this reuses the cache entries for the non-debug workflows, as both debug and non-debug can be run from the same compiler build. Here are example keys:

• ocaml-a8e2e13a317facf1cfb9c973dd211ea11b192c1a-linux-x86_64-bytecode-only
• ocaml-bc5083c1d3b773fc3198355494afd2fb4628ff0e-linux-x86_64-bytecode-only
• ocaml-f28bfbcb232b017460cb0ba7f9ec8cf1cf773811-linux-x86_64-bytecode-only

[jmid]

FTR, these are the times for the bytecode debug workflows:

• Bytecode 5.2 debug / Successful in 180m
• Bytecode 5.3 debug / Successful in 182m
• Bytecode trunk debug / Successful in 194m

It seems saying - and excessive - that the fastest ones of those considered take 3h or more. I'll therefore close this for now.