Support nested redirects

[TheJolman]

Current shorter supports mappings like "d": "/discord".

Can support this with a new command, maybe call it alias?

• While shorter add requires a valid URL to map to a slug, shorter alias would map a new slug to an existing one
  • Validate that existing slug exists first

Plan as of 2/25

New alias command with syntax:

/shorter alias <slug> <destination>

Reason: creates distinct separation from existing add command which requires http:// or https:// in the URI.

Changes to service package

New endpoint:

• POST /links/alias

{
    "slug": "newSlug",
    "aliasTo": "existingSlug",
    "isPermanent?": false
}

Omitting PUT and DELETE resources here intentionally. Existing DELETE/{slug} should be able to work with this, and a new PUT doesn't seem necessary for such a simple operation.

KV Schema will be slightly modified such that URL can be something like /myAlias. The server will capture this slug and query KV again to find the true URL.

Limitations

There will be a limit to deeply nested a redirect can be. I'm thinking that limiting this to 1 level deep would create minimal complexity and not be that much of a limitation.

Future additions

Update GET /list html to cleanly display all a shortlink's aliases underneath it.

Changes to bot package

Implement aforementioned alias subcommand

• Either explicitly disallow leading/trailing slashes or internally discard them.