Add Unlock password reprompt for improved privacy/security

[jcisemer]

Further to https://mobile.twitter.com/jcisemer/status/1019324072365383680:

Status Quo:

• once Tron wallet has been imported, repeat use of the Android app v1.1.4.4 does not reprompt for password (or a PIN) to get to the wallet summary
• wallets like http://eidoo.io built for the Bitcoin and Ethereum blockchains have such a security feature, which also helps with user privacy

Feature Request: Add Tron wallet password reprompt to unlock the app for added privacy & security every single time when reopening the app (like http://eidoo.io does), then continue with Wallet summary upon successful authentication