Support combining multiple abs modifiers

[ethanshar]

Description

Support combining multiple abs modifiers

So far we have abs modifiers to quickly position views in an absolute position. We have: absT, absR, absB, absL, etc...
This PR add support for combining multiple abs modifiers, so basically we can do this

<View absB absR>
  <Text>xxxx </Text>
</View>

to position a view at the right bottom of the screen

Changelog

Support passing multiple abs modifiers (e.g absR and absB together)

[lidord-wix]

Really cool!