Fix annotations swallowing comments

[drwl]

This PR attempts to fix a long standing bug that was carried over from the original gem. Comments near an annotation would get removed when adding or updating annotations.

ctran/annotate_models#951, https://github.com/ctran/annotate_models/#warning

Context
Prior to this change, the AnnotateRb and the old gem Annotate would annotate model files in 1 of 2 ways:

1. The "update" method, existing annotations would be found using a regex and then new annotations would be changed in place. If a human made comment was added after the annotation block without a new line, it would get removed during the update process.
2. The "overwrite" method, which would happen when annotations did not exist OR if the :force option was set to true. A regex would be used to find annotation, remove it from the file, and then add annotations again to the file depending on options such as :position.

Relying on regexes to identify annotations in a file made it hard to reason about and hard to change, so most of them were removed and replaced with a custom Ruby file parser using Ripper [1], which makes working with Ruby files deterministic.

This PR makes the following behavioral changes:

• When updating annotations (i.e. annotations exist && force: false), it only updates the annotations and should no longer delete any human comments that are before or after an annotation block
• When generating (no annotations exist in the file) or re-generating annotations (force: true), it removes the annotation block and surrounding whitespace, if it exists, and then depending on the position option, will add annotations before the class declaration or after the class declaration. In the case of re-generating annotations, any surrounding whitespace will be preserved assuming annotations are being written to the same position.

[1] A great write up on Ripper: https://kddnewton.com/2022/02/14/formatting-ruby-part-1.html

[drwl]

This PR is quite big and a good amount of the lines added are due to test cases I added to document the behavior when annotating a single file. There's a bit of polish left to do in terms of refactors, but I will add that in a future PR.