Pass client configuration in 'new_client' function

[volodymyrZotov]

Currently, there is no possibility of configuring httpx.Client when initializing the client using new_client function. The purpose of this issue to add the configuration ability to the new_client function so it would look like this:

def new_client(url: str, token: str, is_async: bool = False, config: httpx.BaseClient) -> Union[AsyncClient, Client]:

The config parameter should be of type httpx.BaseClient so we can pass any options that httpx.Client and httpx.AsyncClient have.

[chrismaddalena]

What is the status of this and the now-closed PR #96? We are trying to use Connect to manage secrets and integrate 1Password, but we have a private Certificate Authority. The Connect server has no issues, but even with the root CA cert installed on the hosts, new_client throws an error stating it can't verify the certificate. We're using the PR for now but would prefer to see this incorporated into an actual release so we aren't tied to the PR.

[mattjacksoncello]

@volodymyrZotov could I get a review on PR #118 which hopefully covers this?
Will probably need to be a 2.0.0 release as I have included the changes from #92