Avoid including vacuum.h in tableam.h and heapam.h.

Avoid including vacuum.h in tableam.h and heapam.h.

Commit 2252fcd427 modified some function prototypes in tableam.h
and heapam.h to take a VacuumParams argument instead of a pointer,
which required including vacuum.h in those headers.  vacuum.h has a
reasonably large dependency tree, and headers like tableam.h are
widely included, so this is not ideal.  To fix, change the
functions in question to accept a "const VacuumParams *" argument
instead.  That allows us to use a forward declaration for
VacuumParams and avoid including vacuum.h.  Since vacuum_rel()
needs to scribble on the params argument, we still pass it by value
to that function so that the original struct is not modified.

Reported-by: Andres Freund <andres@anarazel.de>
Reviewed-by: Andres Freund <andres@anarazel.de>
Reviewed-by: Michael Paquier <michael@paquier.xyz>
Discussion: https://postgr.es/m/rzxpxod4c4la62yvutyrvgoyilrl2fx55djaf2suidy7np5m6c%403l2ln476eadh