Proxy-pallet: Test transactions & drawdowns flow

[didiermis]

Test following flows/extrinsics:

• Send an EB5 drawdown as draft
• Send an EB5 drawdown as submitted
• Approve an EB5 drawdown
• Approve a Construction loan & developer equity drawdown
• Reject a drawdown
• Up bulkupload

Extras:

• Update validations if needed
• Update flows
• Fix bugs

[didiermis]

Backend done.
@tlacloc

[tlacloc]

Closing the ticket as the feature has been merge in #234