[Multi-Tenant] Add a public name, api secret to tenants

[njlie]

A tenant should be able to include a display name when it is being registered, so that this name could be used in the wallet address url for wallet addresses on that particular tenant.

Tenants should also have an apiSecret that should be used to sign requests made by that tenant, and used by the backend service to reconstruct a signature & verify that one sent in the headers is valid.

• Add publicName column
• Add required apiSecret column