feat!: introduce Path as a subset of Url to enforce type safety

[sxyazi]

Prepare for #611

With #3034, Url gained support for virtual filesystem namespaces, which means a scheme can appear in the URL now, so it can be used like this:

local url = Url("sftp://my-server//path/to/file"):strip_prefix("sftp://my-server//path")
print(url)  -- Url("/to/file")

The value returned here is actually a path that does not include the scheme (sftp://my-server/), so returning it as a Url no longer makes sense:

• Url("/to/file") denotes a local file whose path is /to/file.
• But it's a remote file /to/file in the my-server namespace

That ambiguity can create potential security risks, for example, passing it to an API like fs.remove() could end up deleting a local file when the intention was to delete a remote one.

By introducing Path and restricting its usage, for example, fs.remove() accepts only Url and not Path, so that users must explicitly construct a Url from a Path before operating on it, which reduces misuse-driven security risks and enforces type safety:

local path = Url("sftp://my-server//path/to/file"):strip_prefix("sftp://my-server//path")
print(path)  -- Path("/to/file")

local url = Url("sftp://my-server/" .. path)
fs.remove("file", path)  -- Errors out to avoid removing the local file `/to/file` by mistake
fs.remove("file", url)  -- Removes remote file `sftp://my-server//to/file`, which is intentional

⚠️ Breaking change

Url's strip_prefix() method now returns a newly introduced Path type instead of the original Url.

Path exposes all of Url's API except for the scheme. Documentation is available at https://yazi-rs.github.io/docs/next/plugins/types#path