schannel_verify: fix a memory leak of cert_context

[x2018]

When CryptQueryObject returns a context of unexpected type, the cert_context was not freed.
This could be exploited by malicious servers providing specially crafted CA files.

[x2018]

I unify the handling at one place. According to the document of CryptQueryObject at https://learn.microsoft.com/en-us/windows/win32/api/wincrypt/nf-wincrypt-cryptqueryobject, the output type of last parameter (cert_context) is based on the dwContentType (i.e., actual_content_type). So I also try to clean the resource based on actual_content_type.
Other: The API is deprecated. We may need to update the implementation in the future.