CI/Build: Build Gutenberg before installing Core dependencies.

Because of a strange interaction with building Gutenberg from within the plugins directory, TypeScript was appearing to examine code for which it should have no access up the filesystem hierarchy.

This patch changes the order of building Gutenberg so that it occurs before those parent directories contain TypeScript code (by installing the `npm` dependencies) and thus frees up the builds.

This change should not serve as a workaround to avoid fixing the root issue, introduced in WordPress/gutenberg@8401993. Rather, it should be seen as at least a temporary way to remove the trigger of the problem during CI builds.

See also alternative work:

 - To build Gutenberg outside of the plugin directory in https://github.com/WordPress/wordpress-develop/pull/10282/files.
 - To patch the broken `@wordpress/blocks` types inside of `@wordpress/core-data`.

Developed in #10283

Props czarate, desrosj, dmsnell, ellatrix, jorbin, peterwilsoncc, ramonopoly, westonruter, youknowriad.


git-svn-id: https://develop.svn.wordpress.org/trunk@60985 602fd350-edb4-49c9-b593-d223f7449a82

Author: dmsnell

.github/workflows/reusable-test-gutenberg-build-process.yml

@@ -34,9 +34,9 @@ jobs:
   # - Checks out the Gutenberg plugin into the plugins directory.
   # - Sets up Node.js.
   # - Logs debug information about the GitHub Action runner.
-  # - Installs Core npm dependencies.
   # - Installs Gutenberg npm dependencies.
   # - Runs the Gutenberg build process.
+  # - Installs Core npm dependencies.
   # - Builds WordPress to run from the relevant location (src or build).
   # - Builds Gutenberg.
   # - Ensures version-controlled files are not modified or deleted.
@@ -78,9 +78,6 @@ jobs:
           curl --version
           git --version
 
-      - name: Install Core Dependencies
-        run: npm ci
-
       - name: Install Gutenberg Dependencies
         run: npm ci
         working-directory: ${{ env.GUTENBERG_DIRECTORY }}
@@ -89,6 +86,9 @@ jobs:
         run: npm run build
         working-directory: ${{ env.GUTENBERG_DIRECTORY }}
 
+      - name: Install Core Dependencies
+        run: npm ci
+
       - name: Build WordPress to run from ${{ inputs.directory }}
         run: npm run ${{ inputs.directory == 'src' && 'build:dev' || 'build' }}