Add era and modification to query fields

[rodolphecombe]

Adding this two parameters that are present in the description of the replays in https://replays.wesnoth.org/ would allow easily searching for replays using a specific era or modification.
Although this will be mostly useful for the modders, I hope it is not something complex to add.

[soliton-]

The description mentioned here is from https://replays.wesnoth.org not from the dashboard, btw.

The era and modification info is here: https://github.com/wesnoth/wesnoth/blob/d2f6b171c0b878a64c4afd354b303232d87bb490/utils/mp-server/table_definitions.sql#L115-L131

[rodolphecombe]

Yes, sorry, it was not clear in the post. I edited it.
It could actually be added to the result of the queries though.