When ngtsc generates a .ngfactory shim, it does so based on the contents of
an original file in the program. Occasionally these original files have
comments at the top which are load-bearing (e.g. they contain jsdoc
annotations which are significant to downstream bundling tools). The
generated factory shims should preserve this comment.
This commit adds a step to the ngfactory generator to preserve the top-level
comment from the original source file.
FW-1006 #resolve
FW-1095 #resolve
PR Close#29065
866d500324