Add support for BigDecimal in ConvertType processor

[engechas]

Is your feature request related to a problem? Please describe.
When using DDB source, some of the incoming data gets typed as BigDecimal. This type is not supported by the ConvertEntries processor which results in the below exception

Unable to convert key: ****** with value: ****** to ******
java.lang.IllegalArgumentException: Unsupported type conversion. Source class: class java.math.BigDecimal
	at org.opensearch.dataprepper.typeconverter.IntegerConverter.convert(IntegerConverter.java:22) ~[data-prepper-api-2.6.1.jar:?]
	at org.opensearch.dataprepper.typeconverter.IntegerConverter.convert(IntegerConverter.java:8) ~[data-prepper-api-2.6.1.jar:?]
 at org.opensearch.dataprepper.plugins.processor.mutateevent.ConvertEntryTypeProcessor.doExecute(ConvertEntryTypeProcessor.java:68) ~[mutate-event-processors-2.6.1.jar:?]

Describe the solution you'd like
BigDecimal should be added to the supported conversion types

Describe alternatives you've considered (Optional)
A clear and concise description of any alternative solutions or features you've considered.

Additional context
Add any other context or screenshots about the feature request here.

[kkondaka]

For now, if the values are small enough to fit in long/int, conversion to String should work (and if needed, convert it back to integer or long) as a work-around

[Utkarsh-Aga]

Hello @engechas @kkondaka ,
Can I work on raising the PR for this ?

[dlvenable]

@Utkarsh-Aga , That would be great. It would be quite similar to the work you did in #4359.

[Utkarsh-Aga]

Sure, Thanks.
I would work on raising the PR for this.