Add Tailwind CSS language mode (#518)

* Use `esbuild`

* Replace direct `eval`

* add initial language mode

* Update capabilities, add rename provider

* Update vscode types

* Add completion middleware to match built-in CSS provider

* Update language config to match built-in CSS language

* Add folding region completion provider

* Add stylesheet cache

* Add log and error handling

* Update settings handling, debounce validation

* Fix response flakiness by always augmenting CSS

* Respect folding range limit

* Use uncommon symbol as `@media` placeholder

* Update readme

* Use `esbuild` for language server build

* Add `theme()` completion item

* Avoid errors when using `@media screen()`

* Update readme

* Add CSS server to build script

* Rename language mode server file in prod

* Update VS Code `engines` and types versions

* Update grammar

Author: bradlc

package-lock.json

@@ -29,7 +29,7 @@
     "@tailwindcss/typography": "0.5.0",
     "@types/debounce": "1.2.0",
     "@types/node": "14.14.34",
-    "@types/vscode": "1.52.0",
+    "@types/vscode": "1.60.0",
     "builtin-modules": "3.2.0",
     "chokidar": "3.5.1",
     "color-name": "1.1.4",
@@ -57,6 +57,7 @@
     "tailwindcss": "3.0.11",
     "terser": "4.6.12",
     "typescript": "4.2.4",
+    "vscode-css-languageservice": "5.4.1",
     "vscode-languageserver": "7.0.0",
     "vscode-languageserver-textdocument": "1.0.1",
     "vscode-uri": "3.0.2"