Update Python to v3.14.7

[EnterTheArcane]

WHAT / WHY

• Updates Python to 3.14.7-rev1 on Windows-X64, Linux-X64, Linux-ARM, and Mac-ARM.
• Moves the Mac build onto pull_and_build_from_git.py and the O3DE OpenSSL-3.6.3-rev1-mac-arm64 package instead of the installer's own OpenSSL download, and adds a test-python.sh validation step. Linux picks up OpenSSL-3.6.3-rev1 in place of 1.1.1t.
• Adds a static zstd 1.5.7 to the Linux and Mac builds so the new compression.zstd stdlib module is present, and ships LICENSE.ZSTD with every package.
• Adds Scripts/packaging/sign_macos_binaries.py, which signs every Mach-O in the framework. Ad-hoc by default, or a Developer ID with hardened runtime and a secure timestamp when 3PS_MACOS_CODE_SIGN_IDENTITY is set. Bytecode is precompiled for all three optimization levels before signing so first launch does not invalidate the sealed bundle.
• Updates the Mac installer patch for Tcl/Tk 9.0 and raises the deployment target to 13.0.
• Builds Windows with the VS2022 v143 toolset and drops the vendored libexpat copy and the open3d_python.patch, both of which upstream no longer needs.
• Replaces the get-pip.py download, manual pip/setuptools/wheel upgrades, and shebang rewriting with --with-ensurepip=install (ensurepip --upgrade on Windows).
• Fixes latent bugs in the Linux Docker build: LIBFFI_GIT_URL and LIBFFI_LIB_PATH were misspelled, several retVal checks tested a stale value, and the OpenSSL pkg-config files are now rewritten to the downloaded package prefix so a non-relocatable .pc does not break configure.
• Extends quick_validate_python.py to assert the exact version, reject a free-threaded build, import compression.zstd, ensurepip, pip, and venv, and print the SOABI.

distutils was removed in 3.12, so --include-distutils is gone from the Windows layout and consumers that still import it need setuptools. The standard GIL-enabled interpreter is used on every platform. The free-threaded build is intentionally not packaged.

TEST

All GitHub Actions package builds and validations pass.