Allow filtering silences by creator

[m-masataka]

Add silence filter by "createdBy" item.

filter-demo.mov

related to #2476

[roidelapluie]

Hello @w0rm

Could you fancy a chance to review this from a Elm perspective? Thanks!

[w0rm]

@m-masataka @roidelapluie apologies for the delay. Great work as always, looks like a pretty useful feature to me!

I wonder about the necessity to serialise the list of creators to a string and back: {creator1,creator2} vs passing things in URL encoded query vars, e.g. creator=creator1&creator=creator2. The current implementation feels a bit error prone to me, and we have to deal with things like string escaping and the allowlist of characters, while the original input field for the silence creator doesn't have these restrictions:

isVarCharAndSymbol char =
     Char.isLower char
         || Char.isUpper char
         || String.contains (String.fromChar char) "_ .&-^[]:;*+?!#$%&()"
         || Char.isDigit char

Another question I have is usability point of view.

• Do we need to filter by multiple creators? The current created by filter is joined with "OR", that works differently when filtering alerts by matchers, that are joined with "AND".
• The creator field can be any text, there may be typos and extra spaces, not sure this can work reliably. Maybe allowing filtering by regex would mitigate some of that.

From the UI point of view, the button that toggles the created by bar looks a bit weirdly positioned to me, but I think it would be OK to get this merged, and then I can improve (would like to play with a few ideas myself).