refactor: save only one txi for aex9 presence

[jyeshe]

What

• Unifies :derive_aex9_presence with :update_aex9_state
• Moves aex9 presence txi from key to value

Why

1. Task under same :update_aex9_state type for a contract call is de-duplicated if enqueued right afterwards an async task created for a contract create.
2. Update aex9 txi without deleting other record (only the last value is used on aex9 endpoints).
3. Resolves keep only one aex9 account presence per account and contract pair #459 and fixes Endpoint /aex9/balances/account returning duplicates #735

Validation steps

Run the migration bellow and access:
http://localhost:4000/aex9/balances/account/ak_CNcf2oywqbgmVg3FfKdbHQJfB959wrVwqfzSpdWVKZnep7nj4

It shall return deduped entries (around 30).

defmodule AeMdw.Migrations.AddAex9PresenceTxi do
  alias AeMdw.Database
  alias AeMdw.Db.Model
  alias AeMdw.Db.WriteMutation
  alias AeMdw.Db.State
  alias AeMdw.Log

  require Model

  @spec run(boolean()) :: {:ok, {non_neg_integer(), non_neg_integer()}}
  def run(_from_start?) do
    begin = DateTime.utc_now()

    aex9_mutations =
      Model.Aex9AccountPresence
      |> Database.all_keys()
      |> Enum.into(%{}, fn {account_pk, txi, contract_pk} ->
        {{account_pk, contract_pk}, txi}
      end)
      |> Enum.map(fn {key, txi} ->
        m_presence = Model.aex9_account_presence(index: key, txi: txi)
        WriteMutation.new(Model.Aex9AccountPresence, m_presence)
      end)

    State.commit(State.new(), aex9_mutations)

    indexed_count = length(aex9_mutations)
    duration = DateTime.diff(DateTime.utc_now(), begin)
    Log.info("Indexed #{indexed_count} records in #{duration}s")

    {:ok, {indexed_count, duration}}
  end
end