Update code so that the `warn_return_any` check passes.

 feat: add `asdict()` and `to_json()` methods to Gitlab Objects

Add an `asdict()` method that returns a dictionary representation copy
of the Gitlab Object. This is a copy and changes made to it will have
no impact on the Gitlab Object.

The `asdict()` method name was chosen as both the `dataclasses` and
`attrs` libraries have an `asdict()` function which has the similar
purpose of creating a dictionary represenation of an object.

Also add a `to_json()` method that returns a JSON string
representation of the object.

Closes: #1116

Previously the `attributes` method would show the original values in a
Gitlab Object even if they had been updated. Correct this so that the
updated value will be returned.

Also use copy.deepcopy() to ensure that modifying the dictionary returned can
not also modify the object.

This can be used to tell if a `RESTObject` was created using
`lazy=True`.

Add a message to the `AttributeError` if attribute access fails for an
instance created with `lazy=True`.

chore: simplify multi-nested try blocks

Ensure the path elements that are passed to the server are escaped.
For example a "/" will be changed to "%2F"

Closes: #2116

Instead of have a multi-nested series of try blocks. Convert it to a
more readable series of `if` statements.