feature: fast-path for password match in basicauth [non token mode]

[vlahan]

When non-token authentication, e.g direct basicauth is used via the caddy security plugin, each request currently has to go through the costly bcrypt.CompareHashAndPassword method resulting in ~ 4s latency to each call:

go-authcrunch/pkg/identity/password.go

Line 117 in 50f3edc

if err := bcrypt.CompareHashAndPassword([]byte(p.Hash), []byte(s)); err == nil {

Adding a cached fast-path as in the core caddyauth module would significantly improve the call latency for the follow-up requests:

https://github.com/caddyserver/caddy/blob/3b3d67871446ee6bf1921938ef0f16b6112c7ceb/modules/caddyhttp/caddyauth/basicauth.go#L186