feat: add ability for users to convert their password login type to oauth/github login (#8105)

* Currently toggled by experiment flag

---------

Co-authored-by: Bruno Quaresma <bruno@coder.com>

coderd/users.go

@@ -501,6 +501,37 @@ func (api *API) userByName(rw http.ResponseWriter, r *http.Request) {
 	httpapi.Write(ctx, rw, http.StatusOK, db2sdk.User(user, organizationIDs))
 }
 
+// Returns the user's login type. This only works if the api key for authorization
+// and the requested user match. Eg: 'me'
+//
+// @Summary Get user login type
+// @ID get-user-login-type
+// @Security CoderSessionToken
+// @Produce json
+// @Tags Users
+// @Param user path string true "User ID, name, or me"
+// @Success 200 {object} codersdk.UserLoginType
+// @Router /users/{user}/login-type [get]
+func (*API) userLoginType(rw http.ResponseWriter, r *http.Request) {
+	var (
+		ctx  = r.Context()
+		user = httpmw.UserParam(r)
+		key  = httpmw.APIKey(r)
+	)
+
+	if key.UserID != user.ID {
+		// Currently this is only valid for querying yourself.
+		httpapi.Write(ctx, rw, http.StatusForbidden, codersdk.Response{
+			Message: "You are not authorized to view this user's login type.",
+		})
+		return
+	}
+
+	httpapi.Write(ctx, rw, http.StatusOK, codersdk.UserLoginType{
+		LoginType: codersdk.LoginType(user.LoginType),
+	})
+}
+
 // @Summary Update user profile
 // @ID update-user-profile
 // @Security CoderSessionToken