Rename `HarborAsyncClient` to `HarborClient`

[pederhan]

harborapi is first and foremost and async package, and as such the main client implementation shouldn't need "Async" tacked onto its name. Having the names HarborAsyncClient and HarborSyncClient is a bit of an eyesore, and it would be better to have HarborClient and HarborSyncClient to denote that the async client is the primary implementation and that the sync client is a modification of the original async client.

In order to not break the installations of current users (all 0 of them), the harborapi and harborapi.client modules should provide HarborClient AND HarborAsyncClient, but with a deprecation warning issued for the latter.

We will need to add some sort of import hook, or perhaps create HarborAsyncClient by subclassing HarborClient and issuing a warning in the constructor:

import warnings

class HarborAsyncClient(HarborClient):
    def __init__(self, *args, **kwargs) -> None:
        super().__init__(*args, **kwargs)
        warnings.warn("HarborAsyncClient is deprecated and will be removed, use HarborClient instead.", DeprecationWarning)

This will of course break IDE auto-completion for the __init__ function of HarborAsyncClient, but that fact combined with the warning should make people switch over to HarborClient.

[pederhan]

Instead of subclassing, we could probably just modify the __new__ method of this hypothetical HarborAsyncClient to return HarborClient instead, so no matter which one you try to instantiate, you always get the same type.

I mean, yeah, a subclassed HarborAsyncClient would pass any isinstance checks for HarborClient but, it's probably better to not introduce a whole new type that can mess things up.