Support textTransform capitalize enum

[macintoshhelper]

I am...

| -------------------------------------------------------------------------------------------------

Requesting a new feature

Proposal/Feature-request:

Support capitalize enum in the CSS textTransform property for React Native and web feature parity, as mentioned in #495 .

I think this will need to be a manual transformation applied to the text string children, and we need to decide what TextTransform enum will be passed onto the Sketch file: none is probably best.

[mathieudutour]

Indeed. The tricky part is when using shared text styles I think