Closes #252.

- Adds a named "init_statement" node for all applicable locations (if,
  switch, while, and range-for)
- Adds alias declarations and typedef declarations to possible types of
  init statements (c++20/c++23)

!! Breaking change due to restructuring and renaming of scoped identifiers !!

Scoped identifier rules have been renamed to "qualified_x_identifier"
and all variants are aliased so they appear as simply
"qualified_identifier" in the syntax tree. This name better reflects the
c++ standard's language describing this concept.

Qualified identifier rules are now always the "parent" with a right
associative rule that lets them nest indefinitely. Each rule terminates
with some kind of non-scope identifier.

This commit also adds support for the 'template' keyword where required
to disambiguate dependent template names. Field accessors (., ->) can be
followed by keyword template before a template method. The scope
resolution operator can be immediately followed by the 'template'
keyword to indicate the following dependent name with '<' is actually a
template and shouldn't be parsed as a binary operator. These keywords
are required for dependent names in these contexts.

Test cases for correct parsing of co_return and co_yield statements as
well as co_await expressions are added to the corpus.

* Fix declaration in if/switch/while conditions

* Simplify structure of if/while/switch conditions

* Assignment LHS can be a scoped identifier

* Bad path in grammar

* Forgot test and parser

* Update for latest tree-sitter-c

* Handle throw and noexcept specifiers

* Don't change ts-c path

* Fix ctor/dtor with attributes

* Handle 'throw'

Fixes #16

Co-Authored-By: Thomas Johansen <thomasjo@gmail.com>