Adopt typed throws to provide callers with more information about possible raised errors

[d-ronnqvist]

Bug/issue #, if applicable:

Summary

This PR adopts SE-0413 where possible to provide callers with more information about possible raised errors.

• ac7eeae updates code where the caller knew the only possible errors were raised but needed a redundant catch block to satisfy the compiler:

  do {
      try doSomething()
  } catch let error as KnownError {
      // ...
  } catch {
     fatalError("`doSomething()` only throws `KnownError`")
  }

  By providing the compiler with information about the errors that doSomething() can raise, the compiler can verify that the implementation doesn't unintentionally raise any other errors and the default catch block provides an error value of the right type:

  do {
      try doSomething()
  } catch {
      // `error` is already bound to a `KnownError` value here
  }

• e8465bc updates a few additional methods that only raise a single type of error to provide this information to the caller, even if there's no callers to update.

• ac7eeae updates some of our helper methods to use throws(E) instead of rethrows so that typed error information isn't lost when using these helpers.

Dependencies

None.

Testing

Nothing in particular. This isn't a user-facing change.

Checklist

Make sure you check off the following items. If they cannot be completed, provide a reason.

• Added Updated tests
• Ran the ./bin/test script and it succeeded
• [ ] Updated documentation if necessary

[d-ronnqvist]

@swift-ci please test

[heckj]

Nice example of using typed errors

[d-ronnqvist]

@swift-ci please test

[d-ronnqvist]

@swift-ci please test

[d-ronnqvist]

The CI issue will be resolved by #1308

[d-ronnqvist]

@swift-ci please test