Go's semantic import versioning requires v2+ modules to include the
major version in the module path. This enables using proper version
tags (v3.x.x) instead of pseudo-versions.
Updated module path: code.gitcaddy.com/server/v3
In history (from some legacy frameworks), both `:name` and `name` are
supported as path path name, `:name` is an alias to `name`.
To make code consistent, now we should only use `name` but not `:name`.
Also added panic check in related functions to make sure the name won't
be abused in case some downstreams still use them.
