fix(NODE-6059): clean up experimental APIs

[nbbeeken]

Description

What is changing?

• Remove parseToStructure
• Fix NumberUtils and ByteUtils this type issue
• Move BSONOffsetError to top-level export along with other errors
• Move getSize to NumberUtils
  • Add wrapper to support bson specific message and error type

Is there new documentation needed for these changes?

No

What is the motivation for this change?

A portion of these APIs are not going to be used, and there was some TS convenience issues.

Double check the following

• Ran npm run check:lint script
• Self-review completed using the steps outlined here
• PR title follows the correct format: type(NODE-xxxx)[!]: description
  • Example: feat(NODE-1234)!: rewriting everything in coffeescript
• Changes are covered by tests
• New TODOs have a related JIRA ticket