* Removes the connection established flag as it should not be necessary.
* Deleting the client instance from the `onDisconnect` callback is now supported.
* `NimBLEDevice::deleteClient` no longer blocks tasks
* Adds a new `Config` struct to `NimBLEClient` to efficiently set single bit config settings.
* Adds `NimBLEClient::setSelfDelete` that takes the bool parameters `deleteOnDisconnect` and `deleteOnConnectFail`
  This will configure the client to delete itself when disconnected or the connection attempt fails.
* Adds `NimBLEClient::setConfig` and `NimBLEClient::getConfig` which takes or returns a `NimBLEClient::Config` object respectively.

* Reword `BLE_HS_EAPP` error string to be more accurate.

Replaces `NimBLEDevice::setConnectionInProgress` and `NimBLEDevice::isConnectionInProgress()` with lower level checks to avoid potential incorrect state reporting.
`NimBLEClient::connect` will instead call `NimBLEScan::stop` if it stopped the scan to release any resources waiting, the call the callback if set.