account abstraction support nexus

[tuna1207]

Motivation and Context

Support nexus smart account

Jira Link: https://toruslabs.atlassian.net/browse/PD-4117?atlOrigin=eyJpIjoiY2FkYzk4M2Y2ZDNlNGFiYmE4Zjg5NDJkYzgwN2E1ZDkiLCJwIjoiaiJ9

Description

Add nexus smart account support.
Replace biconomy with nexus in demo since biconomy is deprecated.
Add Base chain to demo.

How has this been tested?

Tested nexus account in demo app

Screenshots (if appropriate):

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)

Checklist:

• My code follows the code style of this project. (run lint)
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have added tests to cover my changes.
• All new and existing tests passed.
• My code requires a db migration.

[chaitanyapotti]

lgtm