Fixes #11802
Closes #8335
Resolves https://discourse.jabref.org/t/shortcuts-for-get-bibliographic-data-from-doi-and-look-up-doi/4468

This PR introduces keyboard shortcuts for the following actions:

• Get bibliographic data from DOI
• Look up DOI

Mandatory checks

• I own the copyright of the code submitted and I licence it under the MIT license
• Change in CHANGELOG.md described in a way that is understandable for the average user (if change is visible to the user)
• Tests created for changes (if applicable)
• Manually tested changed features in running JabRef (always required)
• Screenshots added in PR description (for UI changes)
• Checked developer's documentation: Is the information available and up to date? If not, I outlined it in this pull request.
• Checked documentation: Is the information available and up to date? If not, I created an issue at https://github.com/JabRef/user-documentation/issues or, even better, I submitted a pull request to the documentation repository.