Use InMemoryAccountInfo when using env vars for authentication

[agoncharov-reef]

Re #894

Current behavior:
When users use env vars for authenticating in B2, those credentials are stored in ~/.b2_account_info file which is unexpected by users and exposes B2 secrets to everyone who can read the file.

New behavior (CLI >=v4 only):
If user uses env vars for authentication, console tool uses InMemoryAccountInfo for storing account info and InMemoryCache for caching data.

Exception: when user calls authorize-account or clear-account commands, they store (or clear) credentials on disk even if "env vars authorization" is used.

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This PR also removes b2_api parameter from ConsoleTool class init method. It was used only in tests and allowed passing mocked B2Api instance, however it added complexity to production code in case when special parameters were passed (like --max_download_streams_per_file): those parameters should be passed to B2Api during initialization, but ConsoleTool received already initialized mocked B2Api instance and thus those parameters couldn't be applied.

This is fixed by delegating B2Api initialization to ConsoleTool entirely, and for tests we use monkeypatching which substitutes few functions used to initialize B2Api inside ConsoleTool.