Add ARM emulation to win explorer installer

[one-good-chance]

Allow ARM emulation in the explorer installer

[luisbg]

Correct value, x64compatible is also the non-deprecated spelling since Inno 6.3, and the runner has 6.7.1, so the release build is fine.

Two things worth noting rather than blocking:

• Have you been able to confirm thumbnails actually render on ARM64? The installer still ships the x64 server.dll and registers it via InprocServer32, so this depends on the shell hosting it in an emulated surrogate. CI can't tell us.
• Add aarch64 release artifacts for Linux and Windows #1132 just landed a windows-11-arm job, so we could now build a native ARM64 server.dll and install the matching one (probably the real fix). Happy to open an issue for that.