[backport v2.10.2] Clusters can be created/edited with broken add-on config yaml file

[github-actions]

This is a backport issue for #12323, automatically created via GitHub Actions workflow initiated by @gaktive

Original issue body:

Setup

• Rancher version: v2.9-50aecc403a523ef45c90de73e99ec2cde182f627-head

Describe the bug
Found while testing #12067
Clusters can be created/edited with broken add-on yaml files. We need a yaml validator for the add-on config as they are now displayed in separate tabs.

To Reproduce
1- From the Clusters Management in the UI, hit Create
2- Select rke2, Input your cloud credentials, fill all the mandatory fields, then select a container network add-on
3- Navigate to the container network tab, and brake the yaml file
4- Hit create

Result
UI allows clusters to be created with broken add-on yaml files.

Expected Result
UI must have a yaml validator for the add-on config file, that displays an error message and prevents a cluster to be created if the yaml files are broken. Same behavior should be applied for the edit form.

Screen.Recording.2024-10-22.at.10.24.14.mov

[izaac]

@IsaSih could you take a look once this is ready to test? as you're the upstream reporter.

[IsaSih]

e2e test LGTM. Tests pass as expected, with the UI locking the Create button when the add-on config yaml file is broken on both the create and edit form.

Rancher v2.11-e9f0646414809cbaee8a1de474d8da152b522f06-head

Dashboard | master beef20e