Replace Filter::equal and Filter::unequal with Filter::like and Filter::unlike correspondingly

[raviks789]

depends on Icinga/ipl-stdlib#33

[nilmerg]

Since you're adjusting many usages of Filter::equal here, I think most of them are not necessary.

Consider the query foo=bar. This is an equal comparison. There's no wildcard, so why should it be handled as a Similar condition? ipl-sql already renders Similar conditions the same as Equal conditions if there's no wildcard.

The filter renderer/parser should handle this the same I think. If there's a wildcard, it can only be a Similar or Unlike condition. If there's no wildcard, it's an Equal or Unequal condition.

This way the search bar and other components need to support all types. And can still use Equal in places where Similar is not required.

And don't forget the tests here 😉

[nilmerg]

Just some minor nitpicks, thanks so far! :)