Notably:
* Unified how parens are formatted between (1) when we have a ParensAround, and (2) when we've decided an Apply needs to have parens
* Made unary minus require the be indented to the same level as any other expression continuation. (it used to accidentally have rules meant for binary operators applied)
* Don't apply extra indent to the backpassing continuation in the case that the call does itself require indentation
* Make `try@foo` correctly parse as `try @foo`, so that formatting doesn't change the tree when it adds that space
* Detect more cases where we need to outdent trailing e.g. {} blocks in applies
* Approximately a bagillion other things, 90% of which I added tests for, and none of which affected the formatting of examples or builtins
This was never fully hooked up in platforms, and the plan is to replace the need for this with doing purity-inference on normal `expect` statements.
On the other hand, fuzzing is finding some bugs caused by having a hyphenated keyword, so this is a great time to go ahead and remove it!
* Keywords need to still be recognized if they're followed by ',' as well as a bunch of other operator characters. Notably missing from this list is '-', since that would mess up expect-fx currently.
* Smattering of niche cases of formatting bugs (either non-idempotency, leading to different code, or leading to unparsable code)
* One missing indent call in fmt_collection leading to a panic
Instead of parsing dbg with an expression block, parse the dbg keyword
with no additional arguments. This way the parser treats dbg just like a
variable in function application. We desugar by pattern matching on
`Apply(Dbg, args, called_via)` nodes. This changes the output of syntax
tests since the initial AST is different, but does not change the output
of can or mono.
Add two new errors for dbg in expression position with either no args or
too many args. This is similar to the error behavior of `crash`.
Continue to parse dbg statements with an expression block, as before.
Make `Expr::Dbg` node specific to dbg expressions, add `Expr::DbgStmt`
for dbg statements. Debug expressions don't have a continuation branch.
Support formatting both kinds of `Dbg` nodes.
