bugfix: show extension window if locked regardless of approval

[bitpshr]

The new 1102 implementation short-circuits an enable call if privacy mode is disabled or if a cached approval exists, but the old implementation also checked if the extension was unlocked. I think this is the source of reported issues: we should always act as if no approval exists if the extension is locked, which gives users a chance to unlock it. This matches the functionality of the old implementation.

Resolves #6618

To test:

1. Open a webpage.
2. Call ethereum.enable() from the console.
3. Log in and / or approve.
4. Log out of MetaMask.
5. Call ethereum.enable() again from the console.
6. You should be presented with a login and approval prompt again. Before this PR, nothing would happen.

[metamaskbot]

Builds ready [8c0bc7b]: chrome, firefox, edge, opera

[whymarrh]

This makes sense to me, comparing this change with the old implementation.^[1]

[danfinlay]

Simple fix, and confirmed it works locally.

[karlito636]

Hi guys. I'm not familiar with bug fix flow. When this fix will be available in the chrome extension? or is it already updated?

[whymarrh]

Yes, this is included in version 6.3.5 which was released yesterday.