Adds support for COPY TO/FROM Azure Blob Storage

Supports following Azure Blob uri forms:
- `az://{container}/key`
- `azure://{container}/key`
- `https://{account}.blob.core.windows.net/{container}/key`

**Configuration**

The simplest way to configure object storage is by creating the standard [`~/.azure/config`](https://learn.microsoft.com/en-us/cli/azure/azure-cli-configuration?view=azure-cli-latest) file:

```bash
$ cat ~/.azure/config
[storage]
account = devstoreaccount1
key = Eby8vdM02xNOcqFlqUwJPLlmEtlCDXJ1OUzFT50uSRZ6IFsuFq2UVErCz4I6tq/K1SZFPTOtr/KBHBeksoGMGw==
```

Alternatively, you can use the following environment variables when starting postgres to configure the Azure Blob Storage client:
- `AZURE_STORAGE_ACCOUNT`: the storage account name of the Azure Blob
- `AZURE_STORAGE_KEY`: the storage key of the Azure Blob
- `AZURE_STORAGE_SAS_TOKEN`: the storage SAS token for the Azure Blob
- `AZURE_CONFIG_FILE`: an alternative location for the config file

**Bonus**
Additionally, PR supports following S3 uri forms:
- `s3://{bucket}/key`
- `s3a://{bucket}/key`
- `https://s3.amazonaws.com/{bucket}/key`
- `https://{bucket}.s3.amazonaws.com/key`

Closes #50

src/pgrx_tests/object_store.rs

@@ -338,7 +338,7 @@ mod tests {
         );
 
         let copy_to_command = format!(
-            "COPY (SELECT i FROM generate_series(1,10) i) TO '{}' WITH (format parquet);;",
+            "COPY (SELECT i FROM generate_series(1,10) i) TO '{}' WITH (format parquet);",
             azure_blob_uri
         );
         Spi::run(copy_to_command.as_str()).unwrap();
@@ -365,7 +365,7 @@ mod tests {
         );
 
         let copy_to_command = format!(
-            "COPY (SELECT i FROM generate_series(1,10) i) TO '{}' WITH (format parquet);;",
+            "COPY (SELECT i FROM generate_series(1,10) i) TO '{}' WITH (format parquet);",
             azure_blob_uri
         );
         Spi::run(copy_to_command.as_str()).unwrap();