added a simple switch for AND/OR filtering in 'Advanced Filtering'

When the corresponding checkbox in `Advanced Filtering` is checked, the behaviour of filter will be switched to AND(OR) filtering which depends on the default one.

All KeywordExactFilters, KeywordFilters are switchable by default.
And some ModelFilters are set switchable in `moztrap/view/filters.py`

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@camd
Could you do me a favor and have a try at this patch? Since I don't know if I set any filter switchable which should not be and vice versa by mistake, thanks.

p.s. I'll continue to work on toggle UI and store toggle state in cookies.