Add tooltip and message validation to `typedInput`

[GogoVega]

• [ ] Bugfix (non-breaking change which fixes an issue)
• [x] New feature (non-breaking change which adds functionality)

Proposed changes

TL;DR; This PR adds support for a validation message to all inputs. This allows node validation to be more precise in case of an error.

This PR adds the following features/changes:

• add the getContent method to RED.popover.tooltip
• the validateNodeProperty function will check for an error message in the tooltip
• the validate method of the typedInput handles the input-error class by itself + addition of a tooltip
• typedInput validators now support an error message

This PR is linked to #4450 and was discussed in the Forum.

TODO:

• [ ] normalisePropertyExpression errors are not yet translated - Quid?

Checklist

• [x] I have read the contribution guidelines
• [x] For non-bugfix PRs, I have discussed this change on the forum/slack team.
• [x] I have run npm run test to verify the unit tests pass
• [ ] I have added suitable unit tests to cover the new/changed functionality

[GogoVega]

I like the idea I will modify it 😉 What about normalisePropertyExpression translations? For 4.1?

[knolleary]

I cannot remember if the english messages in that function end up surfacing to the end user. There are lots of messages... wary of making a huge translation burden. I'd keep it on the todo list personally, don't feel strongly either way.