[Parity Signer] Do not ask to scan an address twice for a known account

[lexfrl]

Description

This PR adds an ability to skip the initial scan QR to copy a sender address from the Parity Signer app if its was already scanned before. Currently it uses the address book as it is on the View & Send -> View Address screen.

Also this PR alters (a confusing) wording: instead of saying Unlock your Parity Signer (which is just wrong since we do not "unlock" anything on that stage), I've changed it to Select an account from your Parity Signer. In other words: user don't have to Unlock your Parity Signer to retrieve the account address.
Here is a more reasoning behind that change: it turns out that people are misled due to misunderstanding on how the process is different from a hardware wallet case: in a Singer case, the actual account unlocking happens right (and only) at the moment of signing on the device, never before and never after. So, in reality, the process has more in common with a View Address than with a hardware wallet case, except that user is able to create TX and show it to the Signer to sign.
Suggestions on further improving of the wording are welcome!

Changes

• a title Unlock your Parity Signer -> Select an account from your Parity Signer
• a selector of recent accounts added to make it unnecessary to scan a known account address once again

Steps to Test

1. Go to View & Send
2. Select Parity Signer
3. Scan a QR of account, stored in your Parity Signer
4. Click on Change Wallet
5. Go to View & Send
6. Select Parity Signer
7. Tap on Use a recent account
8. There should be an account you're scanned recently - so, you'll be able to proceed with that
   sender account

Screenshots

Further improvements

• Use a distinct account suggestions list, which is specific to the Signer. E. g. show addressed which was populated only by QR scan on the Parity Signer screen.
• Use ERC-681 for an automatic network switch for the specific account. It applies to the account suggestions list as well as to QR scanner.

Related issues:

#1349
#1945
novasamatech/parity-signer#103

[coveralls]

Coverage remained the same at 54.532% when pulling aefaded on fckt:develop into c213287 on MyCryptoHQ:develop.

[lexfrl]

BTW, why AWS CodeBuild us-east-2 (mycryptobuilds-develop) is failing (introduced by this)? Build restart is needed?