feat(idempotent): Add support for jmespath_options

[michaelbrewer]

Issue #, if available:

Description of changes:

Like for the validator, idempotent utility should allow for extracting an idempotent key using custom functions

Example usage:

We have an api gateway proxy event:

Where event is:

{
   "body": "{\"id\": \"c299229\"}"
}

And c299229 is the idempotent key we want to use:

@idempotent(DynamoDBPersistenceLayer(table_name="foo", event_key_jmespath="powertools_json(body).id"))
def handler(event, context):
    pass

Checklist

• Meet tenets criteria
• Update tests
• Update docs
• PR title follows conventional commit semantics

By submitting this pull request, I confirm that you can use, modify, copy, and redistribute this contribution, under the terms of your choice.

[codecov-io]

Codecov Report

Merging #302 (7df82ff) into develop (d7b4afe) will decrease coverage by 0.03%.
The diff coverage is 80.00%.

@@             Coverage Diff             @@
##           develop     #302      +/-   ##
===========================================
- Coverage    99.71%   99.68%   -0.04%     
===========================================
  Files           87       87              
  Lines         3151     3155       +4     
  Branches       150      151       +1     
===========================================
+ Hits          3142     3145       +3     
  Misses           5        5              
- Partials         4        5       +1     

Impacted Files	Coverage Δ
...wertools/utilities/idempotency/persistence/base.py	98.43% <80.00%> (-0.76%)	⬇️

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[michaelbrewer]

@cakepietoast @heitorlessa i can update the docs, if this feature makes sense?

[heitorlessa]

LGTM after docs mention this -- In all fairness, simply copy and replace what's available in Validations doc, and we can refactor that to make it reusable later.

https://awslabs.github.io/aws-lambda-powertools-python/utilities/validation/#built-in-jmespath-functions

[heitorlessa]

Last change and I'll merge it :)

Here's the inner cache of jmespath parser - used both by compile and search: https://github.com/jmespath/jmespath.py/blob/599b0f7ea650a60f7512233301e70ff8151de0f0/jmespath/parser.py#L84

Here's the subtle difference between compile and search: https://github.com/jmespath/jmespath.py/blob/599b0f7ea650a60f7512233301e70ff8151de0f0/jmespath/__init__.py#L23

Contrary to fastjsonschema that doesn't cache, JMESPath does on both occasions, and keep up to 128 expressions.

[heitorlessa]

Thanks Michael, again! I'm merging as-is, and create a reminder to come back to simplify the internals once I have a better understanding of Tom's implementation.