Add detail in error messages when yarn plugin can't detect backstage version

I was confused for ~15 minutes today when updating to using the yarn
plugin. It was failing in docker but not locally, and I didn't know why.
It turned out to be because I forgot to copy the backstage.json into the
docker image. This was confusing, because the error seemed to indicate I
was failing the semver checks. This change propagates error detail down
the line, so people will see the actual cause. (i.e. missing file, no
version field, semver wrong)

Signed-off-by: Riley Martine <rmartine@integralads.com>

packages/yarn-plugin/package.json

@@ -31,6 +31,7 @@
   },
   "dependencies": {
     "@backstage/cli-common": "workspace:^",
+    "@backstage/errors": "workspace:^",
     "@backstage/release-manifests": "workspace:^",
     "@yarnpkg/core": "^4.4.1",
     "@yarnpkg/fslib": "^3.1.2",