[superfluid] TotalDelegationByValidatorForDenom query

[pysel]

Closes: #2282

What is the purpose of the change

Query for getting all sfs'd assets for each validator

Brief Changelog

added query and test

Testing and Verifying

This change added tests and can be verified as follows:

unit test

Documentation and Release Note

• Does this pull request introduce a new feature or user-facing behavior changes? yes
• Is a relevant changelog entry added to the Unreleased section in CHANGELOG.md? no
• How is the feature or change documented? not documented

[pysel]

Thanks for the review! I will work on it!

[pysel]

@alexanderbez @mattverse changes addressed

[pysel]

@mattverse done