[vcpkg] Use CreateProcess on Windows. Improve EnvVars manipulation and handling. (#9897)

* [vcpkg] Rewrite process spawning on windows to always use CreateProcess, enabling better environment handling

* [vcpkg] Use environment cache to avoid calling vcvars multiple times

* [vcpkg] Increase buffer size while computing hashes

* [vcpkg] Remove unneeded cmd.exe wrapper process on all CreateProcess calls

* [vcpkg] Fix .vcxproj{,.filters}

* [vcpkg] Upgrade Ctrl-C state machine to handle multiple background processes.

* [vcpkg] Fix regression while launching metrics: 'start' can't be passed directly to CreateProcessW

* [vcpkg] Fix typo on non-Windows

* [vcpkg] Fix various uses of >NUL across the code

* [vcpkg] Fix various uses of >NUL across the code

0 files changed, 0 insertions, 0 deletions