Merge status and custom buttons into a filter button

[Corey Burger]

These two buttons may do very different things underneath the surface, but to a
user they are the same. By changing the name to filter, you also keep the
wording consistent with filters on the menu.

After that is done, change the following things:
*remove Not installed - totally useless, as every that is not installed, and the
search does a better job
*Remove Packaged with debconf - I have no idea why this exists, but it will just
confuse users
*Remove Search filter - what search filter? Either specify or remove
*Split out the locally installed and obsolete options, or reword to just locally
installed.
*Reword Upgradeable (upstream) to just Upgradeable (I assume this is for deb
watch, but it doesn't work and your average user is never going to need it)