Infer default credential providers

> I'm thinking something like this in [store.py](https://github.com/developmentseed/obstore/blob/dfaef429a05241921aabe735381211b27fd34a87/obstore/python/obstore/store.py#L709):
>
> (Not sure if all these exist credential providers exist in obstore, but assume that when called with no arguments that these return the vendor's default credential.)
>
> ``` python
> def from_url(...):
> ...
> scheme = _parse_scheme(url)
> vendor_default_credential_providers = {
> "s3": S3CredentialProvider,
> "gcs": GoogleCredentialProvider,
> "azure": AzureCredentialProvider,
> }
>
> vendor_default_async_credential_providers = {
> "s3": S3AsyncCredentialProvider,
> "gcs": GoogleAsyncCredentialProvider,
> "azure": AzureAsyncCredentialProvider,
> }
>
> if credential_provider is None and vendor_default_credential_provider:
> if credential_provider := vendor_default_credential_providers.get(scheme):
> credential_provider = credential_provider()
> elif credential_provider is None and vendor_default_async_credential_provider:
> if credential_provider := vendor_default_async_credential_providers.get(scheme):
> credential_provider = credential_provider()
>
> if scheme == "s3":
> ...
> ```
>
> Implications:
>
> - Existing behaviour of `from_url` is unchanged when new keywords are omitted.
> - Two new keywords added to `from_url`: `vendor_default_credential_provider` and `vendor_default_async_credential_provider`. These allow the user to opt into using an automatically selected vendor default credential provider, and allow the user to specify whether they want it to be synchronous or asynchronous.
> - If one of the new keywords is specified, and `credential_provider` is not explicitly specified, then the appropriate vendor default credential provider will be used.
> - There is a one to one mapping from scheme to default vendor credential providers. Users must still explicitly specify if they need credential providers other than the vendor default credential provider.
>

_Originally posted by @daviewales in [#267](https://github.com/developmentseed/obstore/issues/267#issuecomment-2773995765)_

Start in obstore/python/obstore/store.py at from_url and inspect _parse_scheme plus the available synchronous and asynchronous credential providers. Check how the existing S3, GCS, and Azure paths handle an omitted credential_provider. Done means the two opt-in keywords select the matching vendor provider without changing behavior when omitted, while explicit providers continue to take precedence.

Written by the indexing model from the issue text.