[FEATURE] Enhance Flint covering index with DECIMAL type

[jw-amazon]

Is your feature request related to a problem?
Currently, when I try to create covering index with decimal type, I am getting this error Fail to run query. Cause: unsupported data type: DECIMAL(38,10)

What solution would you like?
Flint covering index should automatically create an underlying OpenSearch index with the appropriate data type instead of throwing out this error.

What alternatives have you considered?
Convert the existing source table columns to a supported column type by Flint covering index, possible double field?

Do you have any additional context?
Issue possible relate to an existing issue 505.