[Feature Request] Add support for LSP highlight group LspReference*

[hronro]

No description provided.

[Pukkah]

I didn't find a suitable color from the palette for LspReference*. I needed one more shade between background_light (used for CursorRow) and medium_gray (Cursor). Using hard intensity I used a color outside its palette (still from global palette)

{
  LspReferenceText = { bg = "#282828" },
  LspReferenceRead = { bg = "#282828" },
  LspReferenceWrite = { bg = "#282828" },
}