Serialize faction as string in game launch message

[BlackYps]

Closes #834

[BlackYps]

One integration test is broken, but I don't know why, because it seems totally unrelated to me.
test_game_ratings in test_teammatchmaker.py fails to finish. I found this in the log:
WARNING RatingService:rating_service.py:293 gps_update_sql resultset is empty for game_id 41956
It seems like the game_player_stats table fails to update correctly.

[Sheikah45]

You need to make sure the integer value is still used for faction to update the game_stats entries

[codecov]

Codecov Report

Merging #835 (7411a0a) into develop (e2dec4b) will not change coverage.
The diff coverage is 100.00%.

Impacted Files	Coverage Δ
server/ladder_service.py	98.27% <ø> (ø)
server/types.py	100.00% <100.00%> (ø)

[BlackYps]

What are we going to do with this, given that we want to reduce the number of open PRs, but v2 is probably a long time away?

[Askaholic]

Well, since I’m not actively working on the server much anymore we should probably release a less ambitious version of the v2 changes that just includes what we have so far. We can always do a v3 later if more stuff gets done.

I have merged some breaking change stuff onto the v2-develop branch which I then occasionally go and rebase onto develop. We could merge this PR there too and release any time since it sounds like the official client can handle this already. So if you rebase this onto v2-develop and change the base branch to that, we can merge.