Context navigation in the Abstract Profile Actions.

[Rod Widdowson]

> The issuer ID doesn't get used
> much if at all, but it will come from
> RelyingPartyContext.getRelyingPartyConfig() I think.

For the record  I was wrong when  I stated that the IssuerId was used only
for filtering.  It also figures as the NameQualifier in
NameID/NameIdentifier construction and also in
CryptoTransientIdAttributeDefinition (which I note is still using the grungy
'!' separated thing - do we want to move this to JSON).

I see that there is currently a route to both SP and IdP EntityID from the
RelyingPartyContext so I'll use that for now, but leave some TODOs in place
to indicate that this is still TBD.

Rod