This PR changes the approach to managing 3rd party DA clients. It was
assumed before that they will be stored in a separate repository
(hyperchain-da), but to simplify the processes and solve a recursive
dependency problem, we decided to manage those within `zksync-era`.

The config now defines which DA client will be used, for proto-based
configuration it requires adding these lines to general.yaml:
```
da_client:
  avail:
    api_node_url: wss://turing-rpc.avail.so/ws
    bridge_api_url: undefined
    seed: SEED_PHRASE
    app_id: 82
    timeout: 3
    max_retries: 5
```
for env-based:
```
    DA_CLIENT="Avail"
    DA_API_NODE_URL="localhost:12345"
    DA_BRIDGE_API_URL="localhost:54321"
    DA_SEED="SEED_PHRASE"
    DA_APP_ID=1
    DA_TIMEOUT=2
    DA_MAX_RETRIES=3
```
If no config is provided - the default behavior is to use NoDA client
(same as now).

The `da_client` config might be merged with `da_dispatcher` at some
point as the second depends on the first one, so their separation does
not make much sense (apart from simplification of the configs). But I'd
prefer to do it as a separate PR in case we decide to merge them.

The client was reimplemented using only lightweight libraries from
crates.io, so it doesn't have any visible impact on build time.

To enable seamless integration with 3rd party DA clients in
`zksync-era`.

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