feat: Add Windows ARM64 (win32-arm64) toolchain support

[petero-dk]

• Add win32-arm64 platform to _PLATFORMS in toolchains_repo.bzl
• Add win32-arm64/windows-arm64 integrity hashes to TOOL_VERSIONS for all esbuild versions that publish a Windows ARM64 binary (0.13.12+)
• Update mirror_release.sh to fetch win32-arm64 hashes for future releases

rules_esbuild only declared toolchains for darwin-x64, darwin-arm64, linux-x64, linux-arm64, and win32-x64. There was no toolchain for Windows on ARM64, even though esbuild publishes a @esbuild/win32-arm64 npm package (and the legacy unscoped esbuild-windows-arm64 package for esbuild < 0.16.0).

The win32-arm64 platform entry is compatible with @platforms//os:windows + @platforms//cpu:aarch64. The existing legacy-name transform (win32 -> windows) already produces the correct old-style key windows-arm64 for esbuild < 0.16.0, so no code change was needed there. Integrity hashes were fetched directly from the npm registry to match the existing format, and added to every version in TOOL_VERSIONS for which esbuild actually publishes a Windows ARM64 binary. Version 0.11.20 predates the Windows ARM64 package's existence, so it intentionally has no windows-arm64 entry; repository rules are lazy, so this only produces an error if someone explicitly requests that exact platform/version combination, consistent with the existing _fail__no_integrity behavior for any other missing hash. No changes were needed in toolchain.bzl, repositories.bzl, or the rest of toolchains_repo.bzl, since they already derive behavior generically from _PLATFORMS / TOOL_VERSIONS.

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Changes are visible to end-users: yes

• Searched for relevant documentation and updated as needed: no
• Breaking change (forces users to change their own code or config): no
• Suggested release notes appear below: yes

Adds support for the Windows ARM64 (win32-arm64) esbuild toolchain, so esbuild_register_toolchains / the esbuild module extension now resolve a native binary on Windows ARM64 hosts.

Test plan

• Manual testing; please provide instructions so we can reproduce:

Ran bazel build //esbuild/... to confirm versions.bzl and toolchains_repo.bzl still load and analyze correctly, and verified via a Python exec of versions.bzl that get_platforms() resolves win32-arm64 (or windows-arm64 for legacy versions) for every entry in TOOL_VERSIONS except 0.11.20, which predates the Windows ARM64 npm package.

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