Add tag validation

[EMaksy]

Description

This pr adds:

• frontend tag validation
• backend tag validation
• new test for wrong tags

When a user wants to create a tag in the frontend, every character of the input is validated.
In the case a forbidden character was used, the frontend will reject the input and don't add the character.
Additionally, a backend validation was added to ensure that the backend is protected when a user tries directly to interact with the backend.

Allowed characters are letters, numbers representable in UTF-8, and the following characters: + - = . , _ : @
This is leaned to the aws tag guidelines, for instance tags
See here: https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/Using_Tags.html

Fixes #464

How was this tested?

Existing tests were adjusted to the new requirements.
A new test was added to check if the wrong tags are handled.

[CDimonaco]

The frontend has some sort of error message on the failed validation?

[EMaksy]

Currently, the frontend does not give user feedback on wrong input.
An UI pop feedback was already discussed and needs to be refined for the future implementation.

[rtorrero]

The frontend has some sort of error message on the failed validation?

I wouldn't add any message, the fact that the invalid character simply doesn't appear on the input box seems to me that it should give enough feedback. A message could be a bit annoying in this context, wdyt?

[EMaksy]

So for me as a user, when I try to create a tag and my input was not added, I get the feeling that something is not working properly. A popup could inform me and show me the allowed character. So I directly can do it right on the second try.

For now this works fine, but I would suggest adding some user feedback in the future.

What do you think, guys?

[dottorblaster]

My thoughts:

• The eslint ignore is fine for now, tinkering with this doesn't stop us merging
• The visual feedback is a lot of work that we can track in a further user story to refine

LGTM