This PR adds filetype highlighting support to block string literals in
the TextMate grammar.
After adding the regex in the `begin` of the block string literal,
`beginCaptures` is used to access the first capturing group of the regex
(which captures the filetype) and apply the `constant.character.escape`
rule.

Closes#3641
Also make minor updates to the skeletal design in
docs/design/name_lookup.md following #2113, as there are no longer any prelude names that are made available to unqualified name lookup by default.
Add `type` to the keyword list in
docs/design/lexical_conventions/words.md, following #2360.
codespell now sees "falsy" as a mis-spelling of either "false" or "falsely"; adding it since I think this it's occasionally used this way in programming. e.g., https://developer.mozilla.org/en-US/docs/Glossary/Falsy
Adjusts to use the new check-copyright support for lines starting with a dash.
TextMate is the go-to definition language for syntax highlighting for editors lack dedicated language support for a given programming language. This patch contains a very minimal, yet functional TextMate bundle definition for Carbon.
This allows Carbon users to import the TextMate bundle into their editors to get basic syntax highlighting for Carbon code until we have a more solid specification for the language (that's when the fun with dedicated plugins/extensions begins!).
**Support**
- String literals with escape codes (currently using C highlighting rules)
- Numeric literals in decimal, hexadecimal and binary (lacks _ separator support though)
- Single and multi-line comments
- Highlighting of all? (let me know if some are missing) keywords in the language
Here is an image of the highlighting in action in IntelliJ Dracula mode
