Remove unuseful search syntax feedback

[DominikVoigt]

This PR removes unuseful feedback from the web search text field, as it is not necessary and provides no advantage.
With the introduction of transformers in #7350, the syntax feedback will be adapted and provide adequate and useful feedback.

Fixes #7349, addresses #7277.

• Change in CHANGELOG.md described (if applicable)
• Tests created for changes (if applicable)
• Manually tested changed features in running JabRef (always required)
• Screenshots added in PR description (for UI changes)
• Checked documentation: Is the information available and up to date? If not created an issue at https://github.com/JabRef/user-documentation/issues or, even better, submitted a pull request to the documentation repository.

[tobiasdiez]

I'm against removing the syntax check. From a user perspective, you want to be notified as early as possible that your search query is not valid and not only after you click the search button. Moreover, showing the query syntax problem as some kind of overlay is nicer than a modal error dialog.

That being said, the user experience can indeed be improved. For example, I'm a fan of a more visual representation of the search query as for example in https://dribbble.com/shots/6323387-Job-Search or http://evoluteur.github.io/structured-filter/index.html

[DominikVoigt]

Yeah, I really like the chips design of
I just wanted to disable the current syntax highlighting as it leads to issues.
I will start working on a chips design using the lucene library for tokenization.

[tobiasdiez]

Nice! Then I would prefer to remove the check in the same PR that also converts to the chip-based design (or in two PRs that are merged directly after each other). Or is the check currently so broken that the fetchers are not useable?

[koppor]

The issues are:

• JabRef currently freezes when searching (When typing a "-" after a long title into web search the application freezes #7349). Users are blocked.
• Including the solution with chips design takes more than a few hours

I believe we can re-add the feedback before a new release (#7411). Assigned the issue to the next milestone.

[Fu188]

I think it is unreasonable to remove the syntax check.

[koppor]

@Fu188 Please not my comment above:

I believe we can re-add the feedback before a new release (#7411). Assigned the issue to the next milestone.

Only users using a non-released version will have no syntax checks. We will work on #7411. This will be possible with our new query syntax, which will be translated to the fetchers. Currently, the user has to know the differences between IEEE, ACM, arXiv and modify the query when changing the fetcher. With the new infrastructure, JabRef will do the translation for you.