Rename `JustifyText`

[ickshonpe]

What problem does this solve or what need does it fill?

• The name JustifyText is quite ugly.
• It's not consistant with rest of the bevy_text types which have a Text- prefix.
• It's not consistant with Linebreak which doesn't have a prefix or suffix.

What solution would you like?

Rename it to Justify. Without any other context, it's natural to assume the name Justify refers to text justification.

[jbuehler23]

@alice-i-cecile any chance i can tackle this one?

[jbuehler23]

Ah - ignore, i see there is a PR for this one already