[IQTree] new recipe for v3.1.2

[danvinci]

Adds a builder for IQ-TREE, maximum-likelihood phylogenetic inference. The JLL ships the iqtree3 executable.

Resolves #7097, bumped to v3.1.2 (the active iqtree3 upstream).

Build notes:

• lsd2 and cmaple are git submodules of iqtree3. Fetched as separate GitSources and relocated in the script. Upstream ships only platform-binary release archives, not source tarballs.
• Platforms restricted to 64-bit x86_64 and aarch64. Upstream doesn't support 32-bit and hardcodes -msse3/-mavx/-mfma on any non-ARM target, so powerpc64le and riscv64 fail in vectorclass and pll. Matches upstream's release matrix (Linux/macOS x86_64+ARM, Windows x86_64).
• julia_compat set to 1.10. Zlib_jll pinned to 1.2.13 and CompilerSupportLibraries_jll to 1.0.5, matching what Julia 1.10 ships as stdlib. Older Julia bundles an incompatible Zlib_jll, which would silently break Pkg.add at install time. aarch64-unknown-freebsd dropped: Julia 1.10-1.12 stdlib Zlib_jll (1.2.13+1, 1.3.1+0) has no aarch64-freebsd binary.
• Four patches in bundled/patches/:
  • openmp-find-package.patch: bundled lib/libomp.a is glibc-only on Linux (references __sysconf, fails on musl), and libmac/libomp.a references ___chkstk_darwin on x86_64 macOS, which BB's clang-rt doesn't ship. Switched both branches to find_package(OpenMP): libgomp via CompilerSupportLibraries_jll on Linux, libomp via LLVMOpenMP_jll on macOS/FreeBSD. (aarch64 macOS isn't affected by chkstk_darwin.)
  • cmaple-openmp-find-package.patch: cmaple ships its own bundled libomp.a chain, separate from iqtree3's. Same fix, applied to cmaple/CMakeLists.txt.
  • respect-cross-compile-osx-arch.patch: upstream uses uname -m on the build host for OSX_NATIVE_ARCHITECTURE, which returns x86_64 under BB cross-compile from Linux and breaks aarch64-apple-darwin. Reads CMAKE_OSX_ARCHITECTURES first.
  • cmaple-disable-lto.patch: cmaple turns on LTO unconditionally on macOS / Linux x86_64 / FreeBSD. Archive link fails on cross-toolchains without llvm-ar.
• -march / -mcpu scrubbed across all CMakeLists.txt (BB rejects forced microarchitecture flags; iqtree3 hardcodes them in three places).
• COMMAND copy in iqtree3's Windows post-build steps replaced with COMMAND ${CMAKE_COMMAND} -E copy. The Windows shell copy isn't available in the mingw cross-compile sandbox.
• AppleDouble sidecars dropped from the rootfs CMake modules dir. BB's tar unpack leaves ._* files on macOS hosts that trip CMake compiler detection; no-op on Linux CI.

[lgoettgens]

Have you tried upstreaming the patches? We usually prefer not carrying huge patches alongside the recipes, if possible.

[danvinci]

I opened this PR on a whim as it would have closed #7097, but that issue is old and I'm unsure about downstream Julia users that would actually benefit from this _jll + having this as an addition in the general registry.

Thinking of just saving the patches for now - do you think all of them are worth up-streaming?