FetchContent: Ignore EXACT for redirected find_package() calls

When FetchContent_MakeAvailable() populates a dependency for which
find_package() integration is enabled, all future calls to find_package()
MUST succeed using the contents of the redirection directory. The
generated config version file was not handling calls where the EXACT
keyword was given, resulting in such calls rejecting the redirection
directory's contents and continuing its search. It is not allowed to do
that. Fix the generated file to also set PACKAGE_VERSION_EXACT to
true so that calls with EXACT now accept it, as was originally intended.

Fixes: #23950
3 files changed