feat(coc_nvim): add integration with coc_nvim

lua/catppuccin/core/integrations/coc_nvim.lua

@@ -0,0 +1,25 @@
+local M = {}
+
+local util = require("catppuccin.utils.util")
+
+function M.get(cp)
+    local error = cp.red
+    local warning = cp.yellow
+    local info = cp.sky
+    local hint = cp.teal
+
+    return {
+        -- These groups are for the coc.nvim documentation (https://github.com/neoclide/coc.nvim/blob/master/doc/coc.txt#L2365).
+        CocErrorHighlight = { fg = error },
+        CocErrorSign = { fg = error },
+        CocErrorVirtualText = { fg = error },
+        CocHintHighlight = { fg = hint },
+        CocHintSign = { fg = hint },
+        CocHintVirtualText = { fg = hint },
+        CocInfoHighlight = { fg = info },
+        CocInfoSign = { fg = info },
+        CocInfoVirtualText = { fg = info },
+        CocWarningHighlight = { fg = warning },
+        CocWarningSign = { fg = warning },
+    }
+end