Add new invalid sb base dir error message and validator function

[andrewortwein]

We will now check if the storybookBaseDir is valid before letting the build continue. If it is not defined but needs to be, or is defined but does not point to the correct location, the build will fail and an error will be displayed.

QA

1. Use an app that has TurboSnap enabled
2. Commit a visual change
3. Using the canary build, run a build with --only-changed and an invalid --storybook-base-dir
   • e.g. npx chromatic@<CANARY_VERSION> --only-changed --storybook-base-dir "src/foobar"
4. Verify that the build fails with an error message indicating that the Storybook base dir is invalid
   • Prior to this change, the build would complete successfully, incorrectly detecting no visual changes

📦 Published PR as canary version: 12.0.0--canary.921.8007225252.0

✨ Test out this PR locally via:

npm install chromatic@12.0.0--canary.921.8007225252.0
# or 
yarn add chromatic@12.0.0--canary.921.8007225252.0

[andrewortwein]

@ghengeveld some unrelated tests are now breaking because of the check I put in upload.ts. Am I making assumptions about stats.modules that might not always be true?

[ghengeveld]

Nice. Needs a little work to safeguard performance but otherwise looks good.

[thafryer]

LGTM

[ghengeveld]

🚀 PR was released in v11.0.0 🚀