per-scope `JSR_URL`

[teidesu]

in many cases it makes sense to have a separate registry limited to a single scope, similarly to how it's possible in npm

the use-cases for this range from enterprise packages published to a self-hosted instances to various kinds of integration tests, and would also allow to not "populate" the local jsr instance with upstream packages in many cases.

with npm we can use either .npmrc or an env variable npm_config_@scopename:registry

i suggest deno should support something similar with the JSR_URL env variable, something like JSR_URL_mycompany=https://jsr.mycompany.org maybe?

and ideally this should also be persisted somewhere, not just an env variable, but that's probably for another feature request

[teidesu]

someone suggested that a nice solution for this might be supporting something along jsr://<domain>/<scope>/<name>