Make manage filters modal more userfriendly

[heralden]

There is too much going on!

Suggestion from @yochannah

make it a wizard maybe, that walks the user through adding filters in, step by step.

There's also a problem with the current filter modal that you're not able to add constraints to arbitrary paths; you're limited to the paths that are present as columns. The only way to solve this would be with a query tree interface, similar to the Add columns modal (would it be possible to reuse this?)

Edit: Look at how the original im-tables does this for inspiration.