api: Add missing GET teams endpoints (#5382)

* api: Add an endpoint to list a particular member of team.

* models: Rename `GetUserTeams()` to `GetUserOrgTeams()` in `org_team` model.

`GetUserTeams()` sounds a bit misnomer since it actually returns
the teams that user belongs to in a given organization rather than
all the teams across all the organization that the user has joined.

* models: Add `GetUserTeams()`.

Returns all the teams that a user belongs to.

* api: Add an endpoint for GET '/user/teams'.

A GET request to this endpoint lists all the teams that a user
belongs to.

vendor/code.gitea.io/sdk/gitea/hook.go

@@ -371,6 +371,7 @@ type PushPayload struct {
 	After      string           `json:"after"`
 	CompareURL string           `json:"compare_url"`
 	Commits    []*PayloadCommit `json:"commits"`
+	HeadCommit *PayloadCommit   `json:"head_commit"`
 	Repo       *Repository      `json:"repository"`
 	Pusher     *User            `json:"pusher"`
 	Sender     *User            `json:"sender"`