Fix text color in the event log console when applying dark mode

[dlyrsk]

Fix text color in the event log console when applying dark mode by setting text color to -fx-text-base-color. Also, fix the font size of icons before warning logs.

Fixes #9732

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1. Change in CHANGELOG.md described in a way that is understandable for the average user (if applicable)
2. Tests created for changes (if applicable)
3. Manually tested changed features in running JabRef (always required)
4. Screenshots added in PR description (for UI changes)
5. Checked developer's documentation: Is the information available and up to date? If not, I outlined it in this pull request.
6. 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.

Fixed event log console:
Dark mode:

Light Mode:

[koppor]

For a follow-up request, you could even more optimize the appearance:

For one-line log messages, they could be centered (!) in the line. currently, they are alinged on top. Especially for the icon, this loocks add.

[dlyrsk]

For a follow-up request, you could even more optimize the appearance:

For one-line log messages, they could be centered (!) in the line. currently, they are alinged on top. Especially for the icon, this loocks add.

Yes, I had a look, and it seems log texts are not centered horizontally. Didn't notice before, though.
Also, the leading icons of log texts need to be centered(not so apparent in the image).
I'll have a look at this later.