[CMSP-486] Add is_solr_query filter

[sboisvert]

Right now it's impossible to turn off Solr for specific types of searches.

Another considered solution was to allow for $query->get( 'solr_integrate' ); to be set to false and have that overwrite the result of $query->is_search() but the filter seems like it would give more flexibility and be clearer in it's goal.

[rwagner00]

I created a ticket to look at this internally, thank you for the PR!

[jazzsequence]

I love this. +100 to more filters. @rwagner00 can you update this with the Jira # and/or update the title.

[rwagner00]

@jazzsequence The ticket is: CMSP-486

[PatelUtkarsh]

I'd also love to have some control using this filter to exclude specific rest api requests.