Dye now can be used to change Sign text color

[alvin0319]

Introduction

Before this PR, the player cannot change the Sign text color by clicking with Dye.

This PR implements changing the Sign text color by clicking with Dye.

Relevant issues

N/A

Changes

API changes

• Added SignText::getBaseColor(): returns the base text color of sign
• Added SignText::isGlowingText(): returns whether Sign text has been changed to glow by the Dye

Behavioural changes

• Player now can change Sign text color by clicking sign with Dye
• SignChangeEvent is now also fired when changing text color or glowing text of sign

Backwards compatibility

N/A

Follow-up

N/A

Tests

https://user-images.githubusercontent.com/32565818/147897958-d1a880c0-e1fc-4ec5-9bac-7ffd874010be.mp4

[dktapps]

The text is not the same after rejoining the server.

Before (using white dye)

After

[dktapps]

This is implemented completely incorrectly. Don't use the wiki for your source of information.

[dktapps]

• The text is not supposed to glow unless using Glow Ink Sac, which is not currently implemented:
• The glow of text can be removed by using Ink Sac.
• Applying colour codes to the text is unnecessary.
• The usage of NBT is incorrect. Bedrock uses a SignTextColor tag, which is an integer containing an ARGB colour code. This means that the PR is significantly overcomplicated (it's as simple as using DyeColor->getRgbValue() to store a Color object, except for black, which should use 0,0,0 - this makes the game show a white border instead of black).

[dktapps]

• There are also sounds that should be played when using dye or ink sacs on signs.

[alvin0319]

Do any other things need to be fixed/changed?

[dktapps]

There are still unresolved review comments.

[alvin0319]

Changed target to PM5 (next-major)

[dktapps]

I've made some modifications to the PR, to handle TextIgnoreLegacyBugResolved properly, tidy up the code and improve some doc comments.