private int findNextTypeId() {
		int n = typesArray.getLastNonEmptyIndex() + 2;
		for (int i = 0; i < n; i++) {
			if (typesArray.get(i) == null) {
				return i;
			}
		}
		return n;
	}
Update stored bookmark and fire program change event for a bookmark which has
had its category or comment changed.  All other fields are immutable.
@param bm bookmark
Ghidra/Framework/SoftwareModeling/src/main/java/ghidra/program/database/bookmark/BookmarkDBManager.java