In this PR, we add two methods to facilitate extension lookup by both extensions,
and non-extensions (e.g., PeerAPI or LocalAPI handlers):
- FindExtensionByName returns an extension with the specified name.
It can then be type asserted to a given type.
- FindMatchingExtension is like errors.As, but for extensions.
It returns the first extension that matches the target type (either a specific extension
or an interface).
Updates tailscale/corp#27645
Updates tailscale/corp#27502
Signed-off-by: Nick Khyl <nickk@tailscale.com>
f28c8d0ec0