[FE] Add disable_collstats and collstats limits fields

disable-collectors

string

Input field where we can write a list of disabled collectors like: dbstats,collstats

stats_collections

string

Input field where the user can write a comma separated list of collection names like: col1,col2

collections_limit

integer

Input field where the user can write a number that acts as the upper limit in the number of collections we ca scrape stats for

databases_limit

integer

Input field where the user can write a number that acts as the upper limit in the number of databases we ca scrape stats for