feat(NODE-6087): add Int32.fromString method

[aditi-khare-mongoDB]

Description

Add static Int32.fromString() method.

What is changing?

Is there new documentation needed for these changes?

Yes, there are new API docs.

What is the motivation for this change?

NODE-3660 user ticket, our validation in the Int32 is lacking. In V7, we will add Int32.fromString(value) validation call into the Int32 constructor's string case.

Release Highlight

Add static Int32.fromString method

This method attempts to create an Int32 type from string, and will throw a BSONError on any string input that is not representable as an Int32.
Notably, this method will also throw on the following string formats:

• Strings in non-decimal formats (exponent notation, binary, hex, or octal digits)
• Strings with non-numeric and non-leading sign characters (ex: '2.0', '24,000')
• Strings with leading and/or trailing whitespace

Strings with leading zeros, however, are allowed

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