Simplify Tailwind implementation

[davestewart]

This PR simplifies the Tailwind config, code location and implementation.

It aims to:

• simplifies the code structure for the plugin developer
• better-communicates final color usage for the plugin user

Code

• scattered config is moved to a single file tailwindConfig.ts (perhaps a stepping stone to custom config, too)
• scattered low-level conversion functions remain in, or moved to conversionTables.ts
• brittle Tailwind code moved from retrieveColors.ts to tailwindColor.ts (simplifying the code and bringing it in line with other platforms)

Main UI

• hex / swatches now reflect final Tailwind colors (Figma's other panels show exact colors)
  • note that colors do not reflect transparency of Figma color
• rounded / custom colors now indicated in comment
• lines can be copy/pasted in scss format
• panel title now "Tailwind Colors" rather than "Colors"

Plugin UI

• Plugin UI now shows correct colors and color names
• Colors are de-duped
• Note that [#hex] is shown for non-rounded colors (rather than just #hex) as this is the actual "class name"

[davestewart]

@bernaferrari – this is now ready to go:

• changes from Add Tailwind support for Figma variables #109 merged in
• some tweaks to the color functionality which was just more logical to do along with the file refactor

It's up to you what you name this PR as; could be:

• Simplify Tailwind implementation, or
• Improve Tailwind color usage information

[bernaferrari]

Either way the name is fine. Thanks for all the help!

[davestewart]

Great! OK, now to move on with the flex wrap stuff

[davestewart]

@bernaferrari

Looks like I introduced a bug with the de-duping of colors for non-Tailwind platforms:

Let me take a look now.