Remove score from /reportEvent

[Half-Shot]

Context: https://matrix.org/docs/spec/client_server/r0.5.0#post-matrix-client-r0-rooms-roomid-report-eventid

This is quite a useless key, as I don't think it was well thought through as to how you would define offensiveness as an integer. If it's taken straight from the user, they are very likely to use the maximum value as it would probably be interpreted as an urgent-ness meter.

Even if hidden behind some checkboxes, how do you define what is more offensive for individuals.

At the very minimum this should be an optional key, but ideally should be thrown straight out as currently all supported matrix clients hardcode a value.

https://github.com/matrix-org/matrix-react-sdk/pull/3290/files#diff-551ca16d6a8ffb96888b337b5246402dR66

[aaronraimist]

Also why is the reason required but "may be blank"? Might as well just be optional.

[turt2live]

probably from a legacy way of doing things. Certainly should be optional these days.