proxmox-backup-debug: add 'api' subcommands

this provides some generic api call mechanisms like pvesh/pmgsh.
by default it uses the https api on localhost (creating a token
if called as root, else requesting the root@pam password interactively)

this is mainly intended for debugging, but it is also useful for
situations where some api calls do not have an equivalent in a binary
and a user does not want to go through the api

not implemented are the http2 api calls (since it is a separate api an
it wouldn't be that easy to do)

there are a few quirks though, related to the 'ls' command:
i extract the 'child-link' from the property name of the
'match_all' statement of the router, but this does not
always match with the property from the relevant 'get' api call
so it fails there (e.g. /tape/drive )

this can be fixed in the respective api calls (e.g. by renaming
the parameter that comes from the path)

Signed-off-by: Dominik Csapak <d.csapak@proxmox.com>
Signed-off-by: Thomas Lamprecht <t.lamprecht@proxmox.com>

src/bin/proxmox_backup_debug/mod.rs

@@ -1,2 +1,3 @@
 pub mod inspect;
 pub mod recover;
+pub mod api;