mem-cache: Add function to move blocks in the tags

mem-cache: Add function to move blocks in the tags

Add a function to allow moving a block's metadata from a source
entry to an invalid destination entry.

Change-Id: I7c8adbcd1133c907f1eea7f69dca983215bc3960
Signed-off-by: Daniel R. Carvalho <odanrc@yahoo.com.br>
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/36576
Reviewed-by: Nikos Nikoleris <nikos.nikoleris@arm.com>
Maintainer: Nikos Nikoleris <nikos.nikoleris@arm.com>
Tested-by: kokoro <noreply+kokoro@google.com>