RateLimiterDynamo: Add key to skip querying ttl

[ollyfg]

TLDR: Adds an option allowing users to skip the check for TTL settings when using the RateLimiterDynamo.

When assessing this library for use in a serverless environment (in this case AWS Lambda), we noticed that there was a significant overhead every time we instantiated a new rate limiter (so every time a new lambda started). This was due to RateLimiterDynamo's behaviour which is to query the table to make sure that the TTL has been set up correctly.

While this is useful behavior on a long-running server, it doesn't make much sense in a serverless environment - once we've validated that the TTL is indeed set up correctly it doesn't make sense to keep checking it again and again and again.

I propose a new option which disables this check, in much the same way that you can disable RateLimiterDynamo's built-in table-creation logic.

[animir]

@ollyfg Hello, thank you! This looks great.
FYI, I'll add a new type for ttlSet attribute to index.d.ts.

[animir]

Released in v 5.0.4.

[animir]

@ollyfg I've added a new option description here https://github.com/animir/node-rate-limiter-flexible/wiki/Options#ttlset
Please, let me know if you think it is good enough.