feat: get rid of zksync_select_fork_vm method

[popzxc]

What 💻

Removes zksync_select_fork_vm from cheatcode strategy.
This is done majorly by changing the logic of execution:

• For select_fork: we add account to persisted accounts, select VM, and then execute as usual.
• For create_select_fork: we execute createFork cheatcode, then select VM, then execute selectFork cheatcode. Basically, we split the operation into two and do VM selection in between.

Why ✋

With that, there will be no ZKsync-specific logic in cheatcode implementations.