fix(studio): prevent creating empty actions

[laurentlp]

This PR fixes an issue where it was possible to add empty actions to a node. To fix this issue, a validation was added to make sure the form is valid before enabling the submit button.

Before

simplescreenrecorder-2021-09-23_13.46.46.mp4

After

simplescreenrecorder-2021-09-23_13.45.31.mp4

Closes #76 and DEV-1638

[linear]

DEV-1638 "[BUG] It's possible to add an empty action" (botpress/studio #76)

Describe the bug

You can click add action without anything

To Reproduce
Steps to reproduce the behavior:

1. Go to flow
2. Create a node
3. Click "+" sign then add action
4. See action created

Expected behavior
Form validation should catch this. The Add action button should be disabled unless there is something to add.

Environment (please complete the following information):

• OS: macOS
• Browser Chrome
• Browser Version Version 92.0.4515.131 (Official Build) (x86_64)
• Botpress Version 12.25.0
• NodeJS 12.13.0

Additional context
This will break the flow at the added location. Since it's an add function rather than an update function, I think in most cases people should notice it.

---

botpress/studio #76 by @ptrckbp on GitHub

via LinearSync

[EFF]

simple enough. LGTM.

You can wait for @allardy's input but I believe this is fine !

What happens with skills ? does it change anything