[API] let admin check org membership on other users (#10201)

* fix

* fix lint on master

Co-authored-by: zeripath <art27@cantab.net>

routers/api/v1/org/member.go

@@ -135,7 +135,7 @@ func IsMember(ctx *context.APIContext) {
 		if err != nil {
 			ctx.Error(http.StatusInternalServerError, "IsOrgMember", err)
 			return
-		} else if userIsMember {
+		} else if userIsMember || ctx.User.IsAdmin {
 			userToCheckIsMember, err := ctx.Org.Organization.IsOrgMember(userToCheck.ID)
 			if err != nil {
 				ctx.Error(http.StatusInternalServerError, "IsOrgMember", err)