format: standardized property names for proxy support

### What feature or improvement would you like to see?

In general, I think commonly-used properties should aim for consistent property names across drivers. A specific example is for proxies: most drivers that connect via HTTP or HTTPS will also need to support proxying and there's no reason to have different names or properties for each driver.

Start by comparing the proxy-related properties used by the HTTP and HTTPS drivers, as described in the issue. Determine whether a common naming convention can be agreed across drivers; done would require a defined standardized set of property names, but the issue does not identify files or tests.

Written by the indexing model from the issue text.