fix(NODE-5586): Decimal128 fromString performs inexact rounding

[W-A-James]

Description

What is changing?

• Corrected Decimal128.fromString algorithm to match that in mongo-c-driver
• Unskipped Decimal128 spec tests
• Update Decimal128 spec tests

Is there new documentation needed for these changes?

• No

What is the motivation for this change?

NODE-5586

Release Highlight

Decimal128 constructor now throws when detecting loss of precision

Prior to this release, Decimal128 would round numbers with more than 34 significant digits and lose precision. Now, on detecting loss of precision, Decimal128's constructor and Decimal128.fromString will throw a BSONError. This behaviour should have been the default as the Decimal128 class was always intended to be high-precision floating point value. As such, silently rounding is undesirable behaviour.

// previous behaviour
> new Decimal128('10000000000000000000000000000000001')
new Decimal128("1.000000000000000000000000000000000E+34")

// new behaviour
> new Decimal128('10000000000000000000000000000000001')
Uncaught:
BSONError: "10000000000000000000000000000000001" is not a valid Decimal128 string - inexact rounding
    at invalidErr (/home/wajames/js-bson/lib/bson.cjs:1402:11)
    at Decimal128.fromString (/home/wajames/js-bson/lib/bson.cjs:1555:21)
    at new Decimal128 (/home/wajames/js-bson/lib/bson.cjs:1411:37)

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
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• Changes are covered by tests
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