[ax0]

Description

This PR adds an AArch64 Linux build target to the GitHub workflow. This more or less mirrors the X64 build steps while using the same Docker container used in the PortMaster build, thus furnishing a binary with decent compatibility across various retro handheld distros.

Type of change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)

How Has This Been Tested?

Please describe the tests procedure by which you verified your changes.
Provide instructions on how to reproduce.

Test Configuration:

• Hardware: AArch64 retro handheld
• Test steps: Copy bin/lgpt.aarch64 from resulting zip to device and execute.

Checklist:

• I have performed a self-review of my code
• I have commented particularly in hard-to-understand areas
• I have updated CHANGELOG
• I have updated docs/wiki/What-is-LittlePiggyTracker.md reflecting my changes
• I have version bumped in sources/Application/Model/Project.h
• My changes generate no new warnings (build without your change then apply your change to check this)

[djdiskmachine]

Hey this is great!
Do we really need the makefile additions tho? The build job could call make PLATFORM=X64 in an arm environment and we'd get the same output or am I missing something?