Document limits for batch actions

[PaulRBerg]

How many streams can be created in one go, how many can be canceled, etc.

Over the years, we've received several questions about this:

cc @sablier-labs/solidity

[andreivladbrg]

notes for later:

• depends on the chain (diff max block gas)
• depends on the model as the streamed amount is calculated (if there is a LD stream and the current time is between last 2 segments it will cost more)
• since isDepleted is in a different slot, maybe it affects the gas when set true

[PaulRBerg]

As always, we can start small. We don't need to cover all chains. For instance, just Ethereum and Base would be a good starting point.

[PaulRBerg]

Note: after Lockup v4.0 (which introduced granularity), gas costs are no longer a concern for Unlock in Steps. We can have a virtually infinite number of steps since the computations are lazy.