Chat input stays on F11

[UserTeemu]

MAMA, THAT LITTLE PESKY THIEF TOOK MY LOLLIPOP F11 KEY ATE MY MESSAGES!

Description

If not calling GuiChat#initGui for the first time, store chat input field's text before resetting the text field. Then set the text to the stored one.

Context

https://discordapp.com/channels/411619823445999637/429311217862180867/693160605284040844

Anything Else

I hope the F11 keys don't hate me from removing their only food source after LWJGL 2 bugs.

Checklist

• [X] All new Java and Kotlin files have the right copyright header
• [X] I have tested my code by building it locally
• [X] This is not a work-in-progress and is ready for merge
• [X] I am submitting the PR under and understand the terms of the GNU Lesser General Public License v3.0

[ghost]

poggggers