Add cosmos plugin

[anilcse]

Relates to:

Risks

Background

What does this PR do?

This PR adds a plugin to interact with cosmos chains

What kind of change is this?

Features (non-breaking change which adds functionality)

To introduce basic Cosmos functionality to Eliza, which could be further extended.

Documentation changes needed?

My changes do not require a change to the project documentation.

Testing

You can test by setting COSMOS_MNEMONIC, COSMOS_RPC_URL in your .env, and asking Eliza to transfer tokens.