CSS #regions folding

[octref]

Part of #45899

For example, when you have

/* #region */
.foo {
 color: red
}
/* #endregion */

You want to have the folding in it.

I don't think this feature is very helpful. Just to keep record of it.
If people do want it we can consider adding it.

[octref]

@aeschli I fixed it only for comments using #region and #endregion. However in #47300 the screenshots show /* footer */. Should those be supported too or we only support #region and #endregion?

[aeschli]

I'd say just #region and #endregion for now (there are requests to make that user configurable)