Make protocol schemes case-insensitive. #8066
Description
Currently the protocol schemes in the Firebird 3.0+ connection URLs are case-sensitive (Firebrd/fbclient only accepts the lowercase variant).
Similar to RFC 3986, I think we should handle schemes case-insensitively, where lowercase is the canonical form. See https://www.rfc-editor.org/rfc/rfc3986#section-3.1
In other words, Firebird should accept inet://..., INET://..., inet4://..., INET4://..., inet6://..., INET6://..., xnet://... and XNET://... (and mixed case forms) equally.