* caddytls: Add CipherSuiteName and ProtocolName functions
The cipher_suites.go file is derived from a commit to the Go master
branch that's slated for Go 1.14. Once Go 1.14 is released, this file
can be removed.
* caddyhttp: Use commonLogEmptyValue in common_log replacer
* caddyhttp: Add TLS placeholders
* caddytls: update unsupportedProtocols
Don't export unsupportedProtocols and update its godoc to mention that
it's used for logging only.
* caddyhttp: simplify getRegTLSReplacement signature
getRegTLSReplacement should receive a string instead of a pointer.
* caddyhttp: Remove http.request.tls.client.cert replacer
The previous behavior of printing the raw certificate bytes was ported
from Caddy 1, but the usefulness of that approach is suspect. Remove
the client cert replacer from v2 until a use case is presented.
* caddyhttp: Use tls.CipherSuiteName from Go 1.14
Remove ported version of CipherSuiteName in the process.
Along with several other changes, such as renaming caddyhttp.ServerRoute
to caddyhttp.Route, exporting some types that were not exported before,
and tweaking the caddytls TLS values to be more consistent.
Notably, we also now disable automatic cert management for names which
already have a cert (manually) loaded into the cache. These names no
longer need to be specified in the "skip_certificates" field of the
automatic HTTPS config, because they will be skipped automatically.
