chore!: clean up expressions

[calebdw]

Checklist

• All tests pass in CI
• There are enough tests for the new fix/feature
• Grammar rules have not been renamed unless absolutely necessary (1 rules renamed)
• The conflicts section hasn't grown too much (0 new conflicts)
• The parser size hasn't grown too much (master: 2727, PR: 2699)
  (check the value of STATE_COUNT in src/parser.c)

This cleans up some expressions:

• the exponentiation_expression node has been removed and placed under binary_expression
• the error suppression operator has been moved out of unary_op_expression and placed into a top level error_suppression_expression
• fields were added to unary_op_expression and update_expression

Closes #114

[cfroystad]

This is once again great work! Thank you for all you've done to get this parser back up to speed.

This looks correct and should be working nicely. It's a pleasant surprise with the reduced state count!

Since this is a breaking change, we should keep in mind to increase the version number accordingly on the next release - I guess that means incrementing the minor rather than patch since we're yet to reach 1.0