feat(main): support nvim-notify (#132)

Add support for nvim-notify plugin.

The plugin also provides highlight groups for the border color of
the popups in addition to the title and icon colors. However, in
the spirit of zenbones using color conservatively, I decided not
to set the border color a shade of the diagnost color.

lua/zenbones/specs/dark.lua

@@ -438,6 +438,17 @@ local function generate(p, opt)
 
 			FlashLabel                       { bg = p.water.lightness(p1.bg.l + 24), fg = p.fg },
 			FlashBackdrop                    { fg = Comment.fg },
+
+			NotifyERRORIcon                  { DiagnosticError },
+			NotifyERRORTitle                 { DiagnosticError },
+			NotifyWARNIcon                   { DiagnosticWarn },
+			NotifyWARNTitle                  { DiagnosticWarn },
+			NotifyINFOIcon                   { DiagnosticInfo },
+			NotifyINFOTitle                  { DiagnosticInfo },
+			NotifyDEBUGIcon                  { DiagnosticHint },
+			NotifyDEBUGTitle                 { DiagnosticHint },
+			NotifyTRACEIcon                  { DiagnosticHint },
+			NotifyTRACETitle                 { DiagnosticHint },
 		}
 	end)
 	-- stylua: ignore end

lua/zenbones/specs/light.lua

@@ -438,6 +438,17 @@ local function generate(p, opt)
 
 			FlashLabel                       { bg = p.water.lightness(p1.bg.l - 15), fg = p.fg },
 			FlashBackdrop                    { fg = Comment.fg },
+
+			NotifyERRORIcon                  { DiagnosticError },
+			NotifyERRORTitle                 { DiagnosticError },
+			NotifyWARNIcon                   { DiagnosticWarn },
+			NotifyWARNTitle                  { DiagnosticWarn },
+			NotifyINFOIcon                   { DiagnosticInfo },
+			NotifyINFOTitle                  { DiagnosticInfo },
+			NotifyDEBUGIcon                  { DiagnosticHint },
+			NotifyDEBUGTitle                 { DiagnosticHint },
+			NotifyTRACEIcon                  { DiagnosticHint },
+			NotifyTRACETitle                 { DiagnosticHint },
 		}
 	end)
 	-- stylua: ignore end