docs(sdbapi): document /game/:id/join endpoint

docs(sdbapi): escape underscores in API doc

docs(sdbapi): document /game/my_games endpoint

feat(sdbapi): endpoint for getting own games

feat(sdbapi): endpoint for patching game state

feat(sdbapi): add GAMESTATE_CANCELLED

fix(sdbapi): remove redundant checks for user

feat(sdbapi): endpoint for all forming games

WIP(sdbapi): get all forming games

docs(sdbapi): get_forming > all_forming

fix(sdbapi): launching on Alpine

WIP(sdbapi): actions table

WIP(sdbapi): comment out future endpoints

feat(sdbapi): simplify verifying if a user exists

docs(sdbapi): API doc updates

fix(sdbapi): Dockerfile broke after 529726cf

WIP(sdbapi): game creation API

feat(sdbapi): replace gorm.Model with own fields

feat(sdbapi): initial testing

chore(sdbapi): update deps, testify non-indirect