refactor!: update to Neovim 0.7 APIs

* set highlight groups via nvim_set_hl
* define autocommands via nvim_create_autocmd
* port plugin/nvim-treesitter.vim to Lua
* port healthcheck to Lua

plugin/nvim-treesitter.lua

@@ -0,0 +1,121 @@
+-- Last Change: 2022 Apr 16
+
+if vim.g.loaded_nvim_treesitter then
+  return
+end
+vim.g.loaded_nvim_treesitter = true
+
+-- setup modules
+require("nvim-treesitter").setup()
+
+local api = vim.api
+
+-- define autocommands
+local augroup = api.nvim_create_augroup("NvimTreesitter", {})
+
+api.nvim_create_autocmd("Filetype", {
+  pattern = "query",
+  group = augroup,
+  callback = function()
+    api.nvim_clear_autocmds {
+      group = augroup,
+      event = "BufWritePost",
+    }
+    api.nvim_create_autocmd("BufWritePost", {
+      group = augroup,
+      buffer = 0,
+      callback = function(opts)
+        require("nvim-treesitter.query").invalidate_query_file(opts.file)
+      end,
+      desc = "Invalidate query file",
+    })
+  end,
+  desc = "Reload query",
+})
+
+-- define highlights
+local highlights = {
+  TSNone = { default = true },
+  TSPunctDelimiter = { link = "Delimiter", default = true },
+  TSPunctBracket = { link = "Delimiter", default = true },
+  TSPunctSpecial = { link = "Delimiter", default = true },
+
+  TSConstant = { link = "Constant", default = true },
+  TSConstBuiltin = { link = "Special", default = true },
+  TSConstMacro = { link = "Define", default = true },
+  TSString = { link = "String", default = true },
+  TSStringRegex = { link = "String", default = true },
+  TSStringEscape = { link = "SpecialChar", default = true },
+  TSStringSpecial = { link = "SpecialChar", default = true },
+  TSCharacter = { link = "Character", default = true },
+  TSCharacterSpecial = { link = "SpecialChar", default = true },
+  TSNumber = { link = "Number", default = true },
+  TSBoolean = { link = "Boolean", default = true },
+  TSFloat = { link = "Float", default = true },
+
+  TSFunction = { link = "Function", default = true },
+  TSFuncBuiltin = { link = "Special", default = true },
+  TSFuncMacro = { link = "Macro", default = true },
+  TSParameter = { link = "Identifier", default = true },
+  TSParameterReference = { link = "TSParameter", default = true },
+  TSMethod = { link = "Function", default = true },
+  TSField = { link = "Identifier", default = true },
+  TSProperty = { link = "Identifier", default = true },
+  TSConstructor = { link = "Special", default = true },
+  TSAnnotation = { link = "PreProc", default = true },
+  TSAttribute = { link = "PreProc", default = true },
+  TSNamespace = { link = "Include", default = true },
+  TSSymbol = { link = "Identifier", default = true },
+
+  TSConditional = { link = "Conditional", default = true },
+  TSRepeat = { link = "Repeat", default = true },
+  TSLabel = { link = "Label", default = true },
+  TSOperator = { link = "Operator", default = true },
+  TSKeyword = { link = "Keyword", default = true },
+  TSKeywordFunction = { link = "Keyword", default = true },
+  TSKeywordOperator = { link = "TSOperator", default = true },
+  TSKeywordReturn = { link = "TSKeyword", default = true },
+  TSException = { link = "Exception", default = true },
+  TSDebug = { link = "Debug", default = true },
+  TSDefine = { link = "Define", default = true },
+  TSPreProc = { link = "PreProc", default = true },
+  TSStorageClass = { link = "StorageClass", default = true },
+
+  TSTodo = { link = "Todo", default = true },
+
+  TSType = { link = "Type", default = true },
+  TSTypeBuiltin = { link = "Type", default = true },
+  TSTypeQualifier = { link = "Type", default = true },
+  TSTypeDefinition = { link = "Typedef", default = true },
+
+  TSInclude = { link = "Include", default = true },
+
+  TSVariableBuiltin = { link = "Special", default = true },
+
+  TSText = { link = "TSNone", default = true },
+  TSStrong = { bold = true, default = true },
+  TSEmphasis = { italic = true, default = true },
+  TSUnderline = { underline = true },
+  TSStrike = { strikethrough = true },
+
+  TSMath = { link = "Special", default = true },
+  TSTextReference = { link = "Constant", default = true },
+  TSEnvironment = { link = "Macro", default = true },
+  TSEnvironmentName = { link = "Type", default = true },
+  TSTitle = { link = "Title", default = true },
+  TSLiteral = { link = "String", default = true },
+  TSURI = { link = "Underlined", default = true },
+
+  TSComment = { link = "Comment", default = true },
+  TSNote = { link = "SpecialComment", default = true },
+  TSWarning = { link = "Todo", default = true },
+  TSDanger = { link = "WarningMsg", default = true },
+
+  TSTag = { link = "Label", default = true },
+  TSTagDelimiter = { link = "Delimiter", default = true },
+  TSTagAttribute = { link = "TSProperty", default = true },
+}
+
+for k, v in pairs(highlights) do
+  api.nvim_set_hl(0, k, v)
+end