Stop linking workspace root

[dgp1130]

link_workspace_root = True is a bit of an antipattern. This appears to be going away in rules_js / rules_ts.

Instead, we should follow a model of:

• Every JS file is associated with exactly one NPM package.
• Some NPM packages may not be published, kept internal only.
• JS files loaded by multiple NPM packages can use nested_packages to vendor common JS without having to publish internal packages.
• Use relative imports inside a package.
• Use absolute imports across packages.
• Restructure the repository to define what these packages are and how fine/coarse-grained they should be.
  • Basically delete the common/ directory and split it into internal-only packages which are imported via their package names and vendored into each published package which uses them.

This likely means I'll also need to rethink the publishing story and possibly move to a @rules_prerender/* package model, something I want to do anyways, but haven't really gotten around to.

Also see discussion in https://github.com/dgp1130/rules_prerender/issues/8.

[dgp1130]

As part of https://github.com/dgp1130/rules_prerender/issues/50, I need to turn off link_workspace_root for a number of targets to avoid a conflict with package_name = "rules_prerender" in the declarative shadow DOM target. There's no easy path to fixing this conflict aside from dropping link_workspace_root everywhere.

Alternatively, we could rename the workspace to be a different name than rules_prerender, but given that link_workspace_root is going away in rules_js, I don't think this is a viable long term solution.

[dgp1130]

Successfully removed link_workspace_root = True by converting all absolute imports to relative ones. Not elegant, but it's the minimal solution to this problem.

There are still two link_workspace_root = True usages with rollup_bundle(), but that's a different problem I can tackle separately. I think this is good enough to call it fixed.

I'll follow up on the more general project restructuring in https://github.com/dgp1130/rules_prerender/issues/51/.