Adding an option to build the C api for Umpire. (#15238)

* Adding an option to build the C api for Umpire.

This is useful if you need to link to a C code and you're using
a compiler suite that doesn't support fortran.

* Also updating the versions while I'm here.

* Adding conflict: Fortran requires C.

To ease transition and confusion, default to C-bindings being
present.  This shouldn't hurt anyone who is upgrading an existing
installation.