Simplify da layer (#184)
* Delete old da layer * Move kvdb to separate library `module Kvdb` was part of the `sequencer_lib` and I want to use the same interface for the da_node's db * Add new da layer * Add syncing of the da node * Refactor kvdb with GADT so that key value types need to match Before, `module Kvdb` was an interface for using correct _key_ type. Now, the module ensures correct match between _key_ and _value_ types. Having let's say 2 types stored in kvdb, `Post.t` and `User.t`, with corresponding key types `Post_id.t` and `User_id.t`, it's not possible to use `Post_id.t` key with `User.t` value and vice versa. * Integrate into sequencer `Batch.t` gained few fields and mainly, the idea changed from having one da "unit" per batch, to rather have one da "unit" per transaction. The `command_with_action_step_flags` is a command together with flags, wether the `action_state` was stepped in corresponding account update. * Add test for bootstrap * Refactor da_node sync * Fix readme * Fix dummy actions step env For now, the action step flags are all true, as sequencer currently always do the action step if possible. * Add rpc to query the da node signer public key This will be needed for tests at least, where you want in the test to query the key and deploy the outer account with correctly set da committee. Might be useful for other things as well, so I've added it already. * Add comments * Fix rebase * Add option to deploy outer account with initial db * Rename --testing-mode to --random-sk * Remove from da batch as it's redundant * Add readme to the da layer * Rename --node-to-sync to --da-node-to-sync * Separate client rpc functions * Add more comments * Rename da batch to diff * Fix typo * Add possibility to sync with the list of da nodes