Paragraph argument never used in InvalidateBullet

Change-Id: I07ba855e473fb137551e70de9cfa858c5e079324
Resolves: fdo#78151 change style on toggling bullets on master page outliners

"do what I mean"

In master pages prior to this if we toggle bullets on and off the that changes
the *level* of the paragraph. And because the paragraph is effectively a
preview of the equivalent style level, changing the level disconnects it from
the style which is useless for us.

So instead turn the numbering off at the given outline level. In order to
toggle the numbering back split the defaults-setting into a reusable piece that
sets the numbering indent which we can call to toggle numbering back on

Also split out the broadcast style change *and explicit child* broadcast code
into a reusable method, the absence of which left me stumped for well over an
hour as to why my changes only worked on level 1

Change-Id: I311c7f35f1ca7dff1d151c6141ff5faa7f15c5a2