Support specifying TLS options in connection string

[vlasky]

There is currently no support for specifying custom TLS certificate files as options in the Redis connection string.

If you specify a rediss URL in the connection string, redis.ParseURL() always applies the fixed TLS option ServerName as seen in the code below:

https://github.com/go-redis/redis/blob/997118894af9d4244d4a471f2b317eead9c9ca62/options.go#L269-L271

I am seeking for redis.ParseURL() to be enhanced to support the following crypto/tls configuration options

TLSCertPEMFile - path/filename of public key and any intermediate certificates in PEM format
TLSKeyPEMFile - path/filename of private key in PEM format
TLSMinVersion - minimum TLS version supported
TLSMaxVersion - maximum TLS version supported
TLSServerName - optionally used to override the default SNI hostname during TLS handshaking
TLSInsecureSkipVerify - if set true, accepts any certificate presented by the server and any host name in that certificate, to only be used for testing