feat!: align standard captures with upstream

Problem: Sharing highlight queries with upstream tree-sitter and
Helix is difficult.

Solution: Where reasonable, use capture names in tree-sitter's standard
list or Helix's Atom-style hierarchy.

Specifically:

* tree-sitter "standard capture names"
  (3f44b89685/highlight/src/lib.rs (L20-L72)):

  - `@parameter` -> `@variable.parameter`
  - `@field` -> `@variable.member`
  - `@namespace` -> `@module`
  - `@float` -> `@number.float`
  - `@symbol` -> `@string.special.symbol`
  - `@string.regex` -> `@string.regexp`
  - `@text.*` -> `@markup.*` (`strong`, `italic`, `link`, `strikethrough`; with exceptions; see below)
  - `@text.title` -> `@markup.heading`
  - `@text.literal` -> `@markup.raw`
  - `@text.reference` -> `@markup.link`
  - `@text.uri` -> `@markup.link.url` (in markup links)
  - `@string.special` -> `@markup.link.label` (non-url links)
  - `@punctuation.special` -> `@markup.list` (markdown lists only; move subitems from `@text.todo`)

* Helix captures
  (https://docs.helix-editor.com/master/themes.html#syntax-highlighting):

  - `@method` -> `@function.method`
  - `@method.call` -> `@function.method.call`
  - `@text.{todo,warning,note,danger}` -> `@comment.{error,warning,hint,info,todo}`
  - `@text.diff.{add,delete,}` -> `@diff.{plus,minus,delta}`
  - `@text.uri` -> `@string.special.url` (outside markup)
  - `@preproc` -> `@keyword.directive`
  - `@define` -> `@keyword.directive`(`.define`?)
  - `@storageclass` -> `@keyword.storage`
  - `@conditional` -> `@keyword.conditional`
  - `@debug` -> `@keyword.debug`
  - `@exception` -> `@keyword.exception`
  - `@include` -> `@keyword.import`
  - `@repeat` -> `@keyword.repeat`

* cleanup

  - remove some redundant `@conceal` (but still allow it for conceal-only patterns)
  - remove obsolete `@error` (syntax linting is out of scope for this repo)
  - sort, cleanup capture list in `CONTRIBUTING.md`

queries/lua/highlights.scm

@@ -21,13 +21,13 @@
   "while"
   "do"
   "end"
-] @repeat)
+] @keyword.repeat)
 
 (repeat_statement
 [
   "repeat"
   "until"
-] @repeat)
+] @keyword.repeat)
 
 (if_statement
 [
@@ -36,27 +36,27 @@
   "else"
   "then"
   "end"
-] @conditional)
+] @keyword.conditional)
 
 (elseif_statement
 [
   "elseif"
   "then"
   "end"
-] @conditional)
+] @keyword.conditional)
 
 (else_statement
 [
   "else"
   "end"
-] @conditional)
+] @keyword.conditional)
 
 (for_statement
 [
   "for"
   "do"
   "end"
-] @repeat)
+] @keyword.repeat)
 
 (function_declaration
 [
@@ -133,8 +133,8 @@
 ((identifier) @variable.builtin
   (#eq? @variable.builtin "self"))
 
-((identifier) @namespace.builtin
-  (#any-of? @namespace.builtin "_G" "debug" "io" "jit" "math" "os" "package" "string" "table" "utf8"))
+((identifier) @module.builtin
+  (#any-of? @module.builtin "_G" "debug" "io" "jit" "math" "os" "package" "string" "table" "utf8"))
 
 ((identifier) @keyword.coroutine
   (#eq? @keyword.coroutine "coroutine"))
@@ -167,9 +167,9 @@
 
 ;; Tables
 
-(field name: (identifier) @field)
+(field name: (identifier) @variable.member)
 
-(dot_index_expression field: (identifier) @field)
+(dot_index_expression field: (identifier) @variable.member)
 
 (table_constructor
 [
@@ -179,9 +179,9 @@
 
 ;; Functions
 
-(parameters (identifier) @parameter)
+(parameters (identifier) @variable.parameter)
 
-(vararg_expression) @parameter.builtin
+(vararg_expression) @variable.parameter.builtin
 
 (function_declaration
   name: [
@@ -192,7 +192,7 @@
 
 (function_declaration
   name: (method_index_expression
-    method: (identifier) @method))
+    method: (identifier) @function.method))
 
 (assignment_statement
   (variable_list .
@@ -215,7 +215,7 @@
     (dot_index_expression
       field: (identifier) @function.call)
     (method_index_expression
-      method: (identifier) @method.call)
+      method: (identifier) @function.method.call)
   ])
 
 (function_call
@@ -240,7 +240,7 @@
 ((comment) @comment.documentation
   (#lua-match? @comment.documentation "^[-][-](%s?)@"))
 
-(hash_bang_line) @preproc
+(hash_bang_line) @keyword.directive
 
 (number) @number
 
@@ -257,7 +257,7 @@
                . (_)
                .
                (string
-                 content: (string_content) @string.regex)))
+                 content: (string_content) @string.regexp)))
 
 ;("123"):match("%d+")
 (function_call
@@ -266,4 +266,4 @@
     (#any-of? @_method "find" "match" "gmatch" "gsub"))
   arguments: (arguments
                . (string
-                   content: (string_content) @string.regex)))
+                   content: (string_content) @string.regexp)))