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/julia/highlights.scm

@@ -14,11 +14,11 @@
   name: (identifier) @function.macro)
 
 (quote_expression
-  ":" @symbol
-  [(identifier) (operator)] @symbol)
+  ":" @string.special.symbol
+  [(identifier) (operator)] @string.special.symbol)
 
 (field_expression
-  (identifier) @field .)
+  (identifier) @variable.member .)
 
 
 ;;; Function names
@@ -68,18 +68,18 @@
 ;;; Parameters
 
 (parameter_list
-  (identifier) @parameter)
+  (identifier) @variable.parameter)
 (optional_parameter .
-  (identifier) @parameter)
+  (identifier) @variable.parameter)
 (slurp_parameter
-  (identifier) @parameter)
+  (identifier) @variable.parameter)
 
 (typed_parameter
-  parameter: (identifier)? @parameter
+  parameter: (identifier)? @variable.parameter
   type: (_) @type)
 
 (function_expression
-  . (identifier) @parameter) ; Single parameter arrow functions
+  . (identifier) @variable.parameter) ; Single parameter arrow functions
 
 
 ;;; Types
@@ -362,42 +362,42 @@
   ["let" "end"] @keyword)
 
 (if_statement
-  ["if" "end"] @conditional)
+  ["if" "end"] @keyword.conditional)
 (elseif_clause
-  "elseif" @conditional)
+  "elseif" @keyword.conditional)
 (else_clause
-  "else" @conditional)
+  "else" @keyword.conditional)
 (if_clause
-  "if" @conditional) ; `if` clause in comprehensions
+  "if" @keyword.conditional) ; `if` clause in comprehensions
 (ternary_expression
-  ["?" ":"] @conditional.ternary)
+  ["?" ":"] @keyword.conditional.ternary)
 
 (try_statement
-  ["try" "end"] @exception)
+  ["try" "end"] @keyword.exception)
 (finally_clause
-  "finally" @exception)
+  "finally" @keyword.exception)
 (catch_clause
-  "catch" @exception)
+  "catch" @keyword.exception)
 
 (for_statement
-  ["for" "end"] @repeat)
+  ["for" "end"] @keyword.repeat)
 (while_statement
-  ["while" "end"] @repeat)
+  ["while" "end"] @keyword.repeat)
 (for_clause
-  "for" @repeat)
+  "for" @keyword.repeat)
 [
   (break_statement)
   (continue_statement)
-] @repeat
+] @keyword.repeat
 
 (module_definition
-  ["module" "baremodule" "end"] @include)
+  ["module" "baremodule" "end"] @keyword.import)
 (import_statement
-  ["import" "using"] @include)
+  ["import" "using"] @keyword.import)
 (import_alias
-  "as" @include)
+  "as" @keyword.import)
 (export_statement
-  "export" @include)
+  "export" @keyword.import)
 (selected_import
   ":" @punctuation.delimiter)
 
@@ -458,10 +458,10 @@
 
 (boolean_literal) @boolean
 (integer_literal) @number
-(float_literal) @float
+(float_literal) @number.float
 
-((identifier) @float
-  (#any-of? @float "NaN" "NaN16" "NaN32"
+((identifier) @number.float
+  (#any-of? @number.float "NaN" "NaN16" "NaN32"
                    "Inf" "Inf16" "Inf32"))
 
 ((identifier) @constant.builtin