[libsodium] Use official build systems (microsoft#36800)

Drop the complex and undermaintained build system vendored into the
port.
Use msbuild for windows, and autotools otherwise.

Note: Users who change options via triplet files
(`VCPKG_CMAKE_CONFIGURE_OPTIONS`) must/can migrate to the official
options (via `VCPKG_CONFIGURE_MAKE_OPTIONS`; no equivalent for
msbuild?).

Should resolve microsoft#32888 according to my earlier ["the build also succeeds
with the official autoconf build
system."](microsoft#32888 (comment))
Should resolve microsoft#36777.