Split common-stylenames to individual component files (#14374)

Split common-stylenames to individual component files (#14374)

Moved notification and valo-menu styles to the components folder as
well, and added them to the $v-included-components list.

Additional styles are now also controlled with a list variable, which
lists all components whose additional styles should be included in the
build.

Change-Id: Ifb8d49d71622decf8fa0d4875985fcafd908a1f8