More flexing pose implications

BUR #21955 has been approved by @nonamethanks.

create implication side_chest -> flexing
create alias flexing_pecs -> flexing_pectorals

Slowly populating these after working on double biceps pose.
Would appreciate any help to garden it for older posts.

Edit: removed flexing pecs implication to flexing because it's not a pose like double biceps & side chest and could be a more subtle detail.

Not really related to the implication, but side chest sounds like some variant of sideboob or sidepec.

BUR #22178 has been approved by @nonamethanks.

rename side_chest -> side_chest_pose

That's fair I suppose.
Putting this up for a vote.
This would make it consistent with double biceps pose.

The bulk update request #21955 (forum #262995) has been approved by @nonamethanks.

The bulk update request #22178 (forum #263959) has been approved by @nonamethanks.