Use ajv.addSchema to load validation schemas at build

[MSE99]

Checklist

• run npm run test and npm run benchmark
• tests and/or benchmarks are included
• documentation is changed or added
• commit message and code follows the Developer's Certification of Origin
  and the Code of conduct

Uses ajv.addSchema to load all validation schemas while building the code instead of serializing the schema to an object literal that is eventually passed ajv.validate.

Could fix the memory leak discussed in #379

[mcollina]

really good implementation, this seems something we should do anyway.

[mcollina]

@mattbishop can you verify this solves your leak?

[mattbishop]

Yes I will do so.

[zekth]

Excellent

[mattbishop]

Pulling this version in my package.json:

"fast-json-stringify": "MSE99/fast-json-stringify#fix/memory-leak#379",

[mattbishop]

This version is much more in line with 2.7.13, and I can run my load test without memory failures. It's a good fix for my use case.

[RafaelGSS]

LGTM.