[MODERATION] add user blocking API

- Follow up for: #540, #802
- Add API routes for user blocking from user and organization
perspective.
- The new routes have integration testing.
- The new model functions have unit tests.
- Actually quite boring to write and to read this pull request.

(cherry picked from commit f3afaf15c7)
(cherry picked from commit 6d754db3e5)
(cherry picked from commit d0fc8bc9d3)
(cherry picked from commit 9a53b0d1a0)
(cherry picked from commit 44a2a4fd48)
(cherry picked from commit 182025db9c)
(cherry picked from commit 558a35963e)

routers/api/v1/user/user.go

@@ -202,3 +202,80 @@ func ListUserActivityFeeds(ctx *context.APIContext) {
 
 	ctx.JSON(http.StatusOK, convert.ToActivities(ctx, feeds, ctx.Doer))
 }
+
+// ListBlockedUsers list the authenticated user's blocked users.
+func ListBlockedUsers(ctx *context.APIContext) {
+	// swagger:operation GET /user/list_blocked user userListBlockedUsers
+	// ---
+	// summary: List the authenticated user's blocked users
+	// produces:
+	// - application/json
+	// parameters:
+	// - name: page
+	//   in: query
+	//   description: page number of results to return (1-based)
+	//   type: integer
+	// - name: limit
+	//   in: query
+	//   description: page size of results
+	//   type: integer
+	// responses:
+	//   "200":
+	//     "$ref": "#/responses/BlockedUserList"
+
+	utils.ListUserBlockedUsers(ctx, ctx.Doer)
+}
+
+// BlockUser blocks a user from the doer.
+func BlockUser(ctx *context.APIContext) {
+	// swagger:operation PUT /user/block/{username} user userBlockUser
+	// ---
+	// summary: Blocks a user from the doer.
+	// produces:
+	// - application/json
+	// parameters:
+	// - name: username
+	//   in: path
+	//   description: username of the user
+	//   type: string
+	//   required: true
+	// responses:
+	//   "204":
+	//     "$ref": "#/responses/empty"
+	//   "404":
+	//     "$ref": "#/responses/notFound"
+
+	user := GetUserByParams(ctx)
+	if ctx.Written() {
+		return
+	}
+
+	utils.BlockUser(ctx, ctx.Doer, user)
+}
+
+// UnblockUser unblocks a user from the doer.
+func UnblockUser(ctx *context.APIContext) {
+	// swagger:operation PUT /user/unblock/{username} user userUnblockUser
+	// ---
+	// summary: Unblocks a user from the doer.
+	// produces:
+	// - application/json
+	// parameters:
+	// - name: username
+	//   in: path
+	//   description: username of the user
+	//   type: string
+	//   required: true
+	// responses:
+	//   "204":
+	//     "$ref": "#/responses/empty"
+	//   "404":
+	//     "$ref": "#/responses/notFound"
+
+	user := GetUserByParams(ctx)
+	if ctx.Written() {
+		return
+	}
+
+	utils.UnblockUser(ctx, ctx.Doer, user)
+}