Add boolean logic to filters

Description including problem, use cases, benefits, and/or goals

I'm sure this will be a dup but I can't find it have and gone to post this on multiple occasions.

I regularly find myself fighting with the filters available to get a good query to find very specific searches.

For example, I am searching for the issue Saved searches/filters for issues. Searching save search returns no results whereas saved search returns the issue I was looking for. Furthermore, if I search saved search issues.

Twitter handles this well by allowing 'advanced' users to enter verbal boolean operators, many other dev tools use their own query syntax, which I don't like, but its a good example of how the complexity of searches bring value. So using the examples above, with twitter they would read the last query as saved AND search AND issues, you can then logically explicitly search things like search OR issues, which undeniably becomes complex when no parenthesis are involved, for example saved AND search AND issues OR MR could be (saved AND search AND issues) OR MR or saved AND search AND (issues OR MR). I think this could be made simpler using our cool search badges...

"save search" is a full term search so would not return the issue I was after as I specified it definitely should have "save search". This also goes as far as NOT logic withsave BUT NOT search and tagging, for example labels:ux,todos which may seem silly as they are already filters but I'm throwing it out there, having the tags means the search can be scaled a lot further without needing to provide dedicated UI space to filter properties that are not used very often.

Proposal

Add boolean logic and potentially tagging to search.

Links / references

https://support.twitter.com/articles/71577

https://help.github.com/articles/advanced-search/

https://confluence.atlassian.com/jiracoreserver071/advanced-searching-802172562.html (waaaaaaay too overkill, search should do more work for the user)