Crossbuild: `sys.implementation` and `build-details.json`

[sobolevn]

Bug report

After #135667 sys.implementation can now contain supports_isolated_interpreters field, which can be implementation dependent. For example, when building on Linux for WASI target, Linux build will support supports_isolated_interpreters and WASI won't (at least for now). But, since build-details.json is generated on the build machine, it will contain supports_isolated_interpreters=true. Which is not correct for the end environment.

There might be other issues as well.

CC @ericsnowcurrently @freakboy3742