Make getting block number from RPC instead of contract configurable

[Siegrift]

See: #256

There are some chains (arbitrum) for which block.number doesn't work as expected.

This should be made configurable.

[bbenligiray]

With this, airseeker-admin (and the self-funded Nodary Airseeker, and whoever else will use Airseeker) will need to keep a list of chains for which it should enable this in the config, so operationally we will end up having a very similar thing + a more complex config. I think we should just maintain a list of chain IDs hardcoded in Airseeker and patch it as we need to add new chains, and abstract this away from the user.

[Siegrift]

Maybe this should be something in the @api3/chains repo? Aka some flag optional flag that all the packages can consume.

[bbenligiray]

Maybe the same applies to gas cost/gas limit stuff that @bdrhn9 has to handle on a chain by chain basis in logdata-miner. Maybe there should be script that one runs to determine these properties automatically @hiletmis .

[Siegrift]

So a script that determines this automatically in the chains repo? That way these properties can be autogenerated there.

Shall we create an issue in the chains repo for this?

[bbenligiray]

I created api3dao/chains#264 and api3dao/chains#265 but I think getting api3dao/chains#264 right is important and we'll need some help from @bdrhn9 about that

[Siegrift]

I'm adding "blocked" label until this is implemented in chains.

[Siegrift]

See: #314 (comment)

We are not always fetching the block number from the RPC.