[vcpkg_acquire_msys] add 'which' package to default set on Windows

[wrobelda]

Describe the pull request
This adds a which package to vcpkg_acquire_msys and adds it to the list of default packages acquired on Windows in vcpkg_configure_make. which is commonly used by autotools macros, see e.g. https://cs.github.com/?scopeName=All+repos&scope=&q=path%3A*.m4+%60which

By not providing it, many macros will fail their checks with which: command not found, which actually implies the which command itself is missing, not the command which which is supposed to locate.

[Osyotr]

Maybe also add autoconf-archive?

[wrobelda]

Maybe also add autoconf-archive?

It's already in vcpkg_acquire_msys. Adding it to vcpkg_configure_make was discussed recently and found unnecessary for almost all ports, which, in turn, it would slow down. Which I concur with.

EDIT: discussed here: #24870

[JackBoosY]

/azp run

[azure-pipelines]

Azure Pipelines successfully started running 1 pipeline(s).

[JackBoosY]

Waiting for merge #26646 first.