Notifications section

[paleloser]

This PR adds a new section for notifications:

Thanks to this section we will be able to notify the users about the status of ongoing tasks in the background without having to block the whole UI. Some examples are:

• The installation of the workload is moved to the background and we notify the user when the installation is completed (with the respective status and action items)
• If there are errors, we show them through this section: this way the notification is persisted for a given time, and the user decides whether to dismiss it or not

Notifications are stored in the extension backend, thus they won't dissappear between extension updates.

[paleloser]

We can decide whether to include this notification by default or not. This notification can help the user get started in case they don't have much context about the extension or the product.

It is true that right now there's not much content related to the extension in the documentation site. But it may help users to know about how to use some apps.

[paleloser]

❗ Merge after #29 and #27 to ensure the best integration between the features.

[andresbono]

Great feature 😍

Let me share a few small cases that I found a bit odd:

• Now when you install the extension, it doesn't redirect you to "Settings" and the "Applications" view doesn't load because you have not set the credentials. Is it possible to keep redirecting to "Settings" at first? We could also include a quick note about the need of configuring your credentials specifically in the first notification.
• When you click on VIEW DETAILS in a notification of an uninstalled workload, the extension breaks with an unexpected error.
• When I forced an installation error (reinstalling Argo CD without cleaning the CRDs) the workload doesn't exist, so I can't see the details of the error.

[paleloser]

Very valuable feedback @andresbono , the last 3 commits should address your comments:

• c8adb14 manages the workload details page when the workload does no longer exist
• fa98817 changes the notification body in those cases where there's an error during the workload installation
• 971e211 asks the user for authentication when it is not stored previously