In the past, we sometimes hit missing `Symbol#start_with?` and
`Symbol#end_with?`.
63256bc5d7a8e812964d
So I proposed `Symbol#start_with?` and `Symbol#end_with?` to allow duck
typing that methods for String and Symbol, then now it is available in
Ruby 2.7.
https://bugs.ruby-lang.org/issues/16348
Using `String#starts_with?` and `String#ends_with?` could not be gained
that conveniency, so it is preferable to not use these in the future.