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`

tests/query/highlights/capnp/test.capnp

@@ -20,15 +20,15 @@
 # THE SOFTWARE.
 
 @0xd508eebdc2dc42b8;
-# <- @preproc
+# <- @keyword.directive
 #                  ^ @punctuation.delimiter
 
 using Cxx = import "c++.capnp";
-# <- @include
+# <- @keyword.import
 #     ^^^ @type
 #         ^ @operator
-#           ^^^^^^ @include
-#                  ^^^^^^^^^^^ @string
+#           ^^^^^^ @keyword.import
+#                  ^^^^^^^^^^^ @string.special.path
 
 # Use a namespace likely to cause trouble if the generated code doesn't use fully-qualified
 # names for stuff in the capnproto namespace.
@@ -53,7 +53,7 @@ enum TestEnum {
 struct TestAllTypes {
 # <- @keyword
   voidField      @0  : Void;
-# ^^^^^^^^^ @field
+# ^^^^^^^^^ @variable.member
 #                    ^ @punctuation.special
 #                      ^^^^ @type.builtin
   boolField      @1  : Bool;
@@ -150,7 +150,7 @@ struct TestUnionDefaults {
 
 struct TestUsing {
   using OuterNestedEnum = TestNestedTypes.NestedEnum;
-# ^^^^^ @include
+# ^^^^^ @keyword.import
   using TestNestedTypes.NestedStruct.NestedEnum;
 
   outerNestedEnum @1 :OuterNestedEnum = bar;
@@ -179,7 +179,7 @@ struct TestWholeFloatDefault {
   bigField @1 :Float32 = 2e30;
   const constant :Float32 = 456;
   const bigConstant :Float32 = 4e30;
-#                              ^^^^ @float
+#                              ^^^^ @number.float
 }
 
 struct TestGenerics(Foo, Bar) {
@@ -217,7 +217,7 @@ struct TestGenerics(Foo, Bar) {
 #     ^^^^^^^^^ @keyword
         # At one time this failed to compile.
         call @0 () -> ();
-#       ^^^^ @method
+#       ^^^^ @function.method
 #                  ^^ @punctuation.delimiter
       }
     }
@@ -225,14 +225,14 @@ struct TestGenerics(Foo, Bar) {
 
   interface Interface(Qux) {
     call @0 Inner2(Text) -> (qux :Qux, gen :TestGenerics(TestAllTypes, TestAnyPointer));
-#                            ^^^ @parameter
-#                                      ^^^ @parameter
+#                            ^^^ @variable.parameter
+#                                      ^^^ @variable.parameter
   }
 
   annotation ann(struct) :Foo;
 # ^^^^^^^^^^ @keyword
-#            ^^^ @method
-#                ^^^^^^ @parameter.builtin
+#            ^^^ @function.method
+#                ^^^^^^ @variable.parameter.builtin
 
   using AliasFoo = Foo;
   using AliasInner = Inner;
@@ -423,7 +423,7 @@ const genericConstant :TestGenerics(TestAllTypes, Text) =
     (foo = (int16Field = 123), rev = (foo = "text", rev = (foo = (int16Field = 321))));
 
 const embeddedData :Data = embed "testdata/packed";
-#                          ^^^^^ @include
+#                          ^^^^^ @keyword.import
 const embeddedText :Text = embed "testdata/short.txt";
 const embeddedStruct :TestAllTypes = embed "testdata/binary";
 
@@ -452,7 +452,7 @@ const anyPointerConstants :TestAnyPointerConstants = (
 
 interface TestInterface {
   foo @0 (i :UInt32, j :Bool) -> (x :Text);
-#                                 ^ @parameter
+#                                 ^ @variable.parameter
   bar @1 () -> ();
   baz @2 (s: TestAllTypes);
 }