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/bicep/highlights.scm

@@ -1,16 +1,16 @@
 ; Includes
 
 (import_statement
-  "import" @include)
+  "import" @keyword.import)
 
 (import_with_statement
-  "import" @include
-  "with" @include)
+  "import" @keyword.import
+  "with" @keyword.import)
 
 ; Namespaces
 
 (module_declaration
-  (identifier) @namespace)
+  (identifier) @module)
 
 ; Builtins
 
@@ -80,16 +80,16 @@
 ; Parameters
 
 (parameter_declaration
-  (identifier) @parameter
+  (identifier) @variable.parameter
   (_))
 
 (call_expression
   function: (_) 
-  (arguments (identifier) @parameter))
+  (arguments (identifier) @variable.parameter))
 
 (call_expression
   function: (_) 
-  (arguments (member_expression object: (identifier) @parameter)))
+  (arguments (member_expression object: (identifier) @variable.parameter)))
 
 ; Variables
 
@@ -118,16 +118,16 @@
 
 ; Conditionals
 
-"if" @conditional
+"if" @keyword.conditional
 
 (ternary_expression
-  "?" @conditional.ternary
-  ":" @conditional.ternary)
+  "?" @keyword.conditional.ternary
+  ":" @keyword.conditional.ternary)
 
 ; Loops
 
 (for_statement
-  "for" @repeat
+  "for" @keyword.repeat
   "in"
   ":" @punctuation.delimiter)
 
@@ -179,8 +179,8 @@
 (string) @string
 (import_string
   "'" @string
-  (import_name) @namespace
-  "@" @symbol
+  (import_name) @module
+  "@" @string.special.symbol
   (import_version) @string.special)
 
 (escape_sequence) @string.escape