Implement syscall 0x83 (FindAddress) with kernel tests

[Whoneon]

This PR implements numeric syscall 0x83 (FindAddress) in the runtime kernel syscall dispatcher and adds proper tests. This emerged due to issue #90

Changes

• ps2xRuntime/src/lib/ps2_syscalls.cpp
  • added dispatch:
    • case 0x83: FindAddress(...)
• ps2xRuntime/src/lib/syscalls/ps2_syscalls_system.inl
  • implemented FindAddress:
    • inputs: a0=start, a1=end (exclusive), a2=target
    • scans table as 32-bit words
    • returns matching entry address in v0
    • returns 0 if not found
    • supports KSEG alias normalization (addr & 0x1FFFFFFF) for stronger match behavior
• ps2xTest/src/ps2_runtime_kernel_tests.cpp
  • added tests for:
    • found entry
    • KSEG alias match
    • not-found returns zero

Why this shape

• syscall number mapping follows PS2SDK (__NR_FindAddress = 0x83).
• behavior inferred from generated wrappers/call sites that pass (start, end, symbol) and require v0 as an address.
• the implementation is agnostic (no game-specific constants/workarounds).

Out of scope

• 0x74 mapping/semantics (SetSyscall vs current runtime mapping) is intentionally not changed here and will be handled in a separate PR.

[ran-j]

Does this need to be thread safe ?