Update type operators, quotations and other minor fixes

[savq]

Type operators

• Rename subtype_clause to type_clause :
  • Remove subtype operator from typed_expression.
  • Add supertype operator to type_clause.
  • Note that outside definitions, both <: and >: are parsed as comparison operators.
• Add where_expression: The rule where_clause is still needed because where has a different precedence depending on whether it's in a definition / type parameter or if it's a regular expression.

Quotes

• Add assignment operators to quote_expression.
• Change precedence of colon : as identifier.
• Parse primitive type and abstract type as a single token. This enables parsing primitive and abstract as identifiers.
• Add a list of keywords: This enables quoting some keywords without tree-sitter trying to parse their corresponding rule. This can still fail depending on the context, but in most cases it's good enough.

Misc

• Add typed parameters to function_expression.
• Add closed macros to keyword_parameters (they're already allowed in regular parameters).
• Add assignments to ternary_expression.
• Remove generator_expression and allow a trailing _comprehension_clause in any collection.
• Fix arrow, prefix and postfix precedences.
• Fix pipes names.