Allow hyperlight-host to build with x86_64-unknown-linux-musl target

[simongdavies]

This pull request introduces support for building with the musl libc target, updates syscall handling for compatibility, and adds conditional compilation for thread ID initialization. Below is a summary of the most important changes:

Build System Enhancements:

• Added a new build-with-musl-libc target in the Justfile to enable building with the musl libc target (x86_64-unknown-linux-musl). This includes adding the required Rust target and building with the appropriate profile.

Conditional Compilation for musl:

• Updated the LinuxInterruptHandle initialization in HypervLinuxDriver to conditionally define the tid field based on whether the target is musl or not. This ensures compatibility with the musl libc environment.
• Applied the same conditional logic for the tid field in the KVMDriver to maintain consistency across hypervisor implementations.

Syscall Handling:

• Modified the syscalls_allowlist function to use try_into() for converting libc::TCGETS to ensure type safety and compatibility with stricter environments.

[dblnz]

LGTM