Add docs for ExecutionResult.
Simplify `rescue` clause.
Remove unnecessary layer of indirection.
Remove method aliases that we don't need.

Deprecations are still need in 2.99 for these.
Prefer `def self.<name>` over def within `class << self`.
Reformat wrapped trailing conditional.
Further doc improvements.

[ci skip]
Merge pull request #1406 from rspec/code-audit-changes-part-1

Code audit changes part 1