Sets up pnpm workspaces.

This creates a new `pnpm-workspace.yaml` which makes it install `node_modules/` in all the `packages/*` directories. This wasn't necessary before because `rules_prerender` and `@rules_prerender/declarative_shadow_dom` don't have any external dependencies, but it is necessary to install package-specific dependencies.

Also updates `tsconfig.json` to work for any `@rules_prerender/*` packages instead of just `@rules_prerender/declarative_shadow_dom`.

`.bazelignore` needs to be updated as well, but doesn't support globs unfortunately (see bazelbuild/bazel#7093). `node_modules/` verification was also incorrectly being done on the user `.bazelignore` file, rather than `@rules_prerender`'s `.bazelignore` when loaded as an external workspace. Used a `Label()` constructor to fix that.

.bazelignore

@@ -1,5 +1,11 @@
+# Ignore deeply nested `node_modules/` directories.
 node_modules
+packages/declarative_shadow_dom/node_modules
+packages/rules_prerender/node_modules
+
+# Ignore generated files.
 dist
 bazel-out
 
+# Ignore external workspaces in the repository.
 examples/external/

pnpm-workspace.yaml

@@ -0,0 +1,2 @@
+packages:
+  - "packages/*"

repositories.bzl

@@ -13,7 +13,7 @@ def rules_prerender_repositories():
         name = "rules_prerender_npm",
         pnpm_lock = Label("//:pnpm-lock.yaml"),
         npmrc = Label("//:.npmrc"),
-        verify_node_modules_ignored = "//:.bazelignore",
+        verify_node_modules_ignored = Label("//:.bazelignore"),
     )
 
     rules_ts_dependencies(ts_version_from = Label("//:package.json"))

tsconfig.json

@@ -39,7 +39,7 @@
     "baseUrl": "./",                          /* Base directory to resolve non-absolute module names. */
     "paths": {                                /* A series of entries which re-map imports to lookup locations relative to the 'baseUrl'. */
       "rules_prerender": ["packages/rules_prerender"], // Map `rules_prerender` module to its implementation.
-      "@rules_prerender/declarative_shadow_dom": ["packages/declarative_shadow_dom"]
+      "@rules_prerender/*": ["packages/*"],
     },
     // "rootDirs": [],                        /* List of root folders whose combined content represents the structure of the project at runtime. */
     // "typeRoots": [],                       /* List of folders to include type definitions from. */