tests: Fix typo in test_note

tests: Refactor test_note to use template_test_*

tests: Document expected parse task

tests: Use static tokens with static locattions

tests: Document parse error exception codes

src: Rename syntax to token

parse: Remove SyntaxType ...

Once again I find myself in the pattern of having a useless 'type' value
that just complicates my life. In this case the correct appproach is to
output the AST directly.

parse: Check types when clearing notes, add extra tests

syntax: Refactor draw_syntax_random and add draw_syntax_texttoken ...

I realized draw_syntax_classified is the same as draw_syntax_random, so
just merge them.

Also add draw_syntax_texttoken explicitly meant to weed out cases where
token type is not set.

tests: Clarify function documentation

tests: Refactor mid-test assumes in to custom draws ...

This should help with performance as Hypothesis as we no longer need to
do complex unrelated draws first.

tests: Random insert_random to insert_random_within

parse: Handle parent_context in template_parse_invalid

tests: Split up parser tests for empty cases

tests: Use one test per invalid case for text and notes

tests: Add template_parse_invalid

tests: Move insert_random to parse.templates

tests: Add a template for parsing valid syntax

src: Pass a parent context to skip_note

parse: Have skip_note create a PARSE_NOT ParseContext

parse: Allow attaching a ParseContext to a ParseErrorException

tests: parse: Move note tests to their own files