Allow std.http to ignore invalid SSL certificates for debugging purposes

[rliebig]

Tested with zig version: zig-linux-x86_64-0.14.0-dev.217+bd7dda0c5

I am currently writing a small tool in Zig which connects to a HTTPS endpoint using the std.http library and interacts with it using various GET and POST requests. The public facing version is provided with SSL by Let's Encrypt.

I have a non-public facing version which is used for testing purposes. I use a self signed certificate with the local instance to ensure that I can still use SSL. A valid certificate chain would be overkill.

The current std.http endpoint does not allow invalid certificates and throws a invalid certficate exception. This behaviour is desirable for production software. After reading the current source code, it appears, there is no option to handle this error gracefully and continue the request even after an invalid certificate. Similiar to the behaviour of curl -k would be great.