feat(parser): Adds DDB deserialization to DynamoDBStreamChangedRecordModel

[sthulb]

Issue number: #4219

Summary

Changes

Please provide a summary of what's being changed

This change adds deserialisation to DynamoDBStreamChangedRecordModel, allowing for rapid access to:

• Keys
• OldImage
• NewImage

It also adds properties for existing fields.

User experience

Please share what the user experience looks like before and after this change

Before

change = DynamoDBStreamChangedRecordModel(
    ApproximateCreationDateTime=None, 
    Keys={'Timestamp': {'S': 'foo'}}, 
    NewImage=None, 
    OldImage=None, 
    SequenceNumber='123', 
    SizeBytes=112, 
    StreamViewType='NEW_IMAGE'
)

change.Keys['Timestamp']['S'] # returns 'foo'
change.SequenceNumber # returns '123'
...

After

change = DynamoDBStreamChangedRecordModel(
    ApproximateCreationDateTime=None, 
    Keys={'Timestamp': {'S': 'foo'}}, 
    NewImage=None, 
    OldImage=None, 
    SequenceNumber='123', 
    SizeBytes=112, 
    StreamViewType='NEW_IMAGE'
)

change.keys.get('Timestamp') # returns 'foo'
change.sequence_number # returns '123'
...

This change also relocates the DDB deserialiser work introduced in #1619 to it's own file located in aws_lambda_powertools.shared.dynamodb_deseraiizer

Checklist

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• Meet tenets criteria
• I have performed a self-review of this change
• Changes have been tested
• Changes are documented
• PR title follows conventional commit semantics

Is this a breaking change?

This is a breaking change.

RFC issue number:

Checklist:

• Migration process documented
• Implement warnings (if it can live side by side)

Acknowledgment

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[leandrodamascena]

Hi @sthulb! This PR will introduce a great developer experience in Powertools V3, that's super cool!!

Before I review, can you pls add some tests?

[sonarqubecloud]

Quality Gate passed

Issues
1 New issue
0 Accepted issues

Measures
0 Security Hotspots
No data about Coverage
0.0% Duplication on New Code

See analysis details on SonarCloud

[leandrodamascena]

Amazing work @sthulb! Approved.