Changed the color of found text from red to high contrast

[u7232539]

Fixes koppor#552.

This issue is about changing the text color from red to green to avoid misunderstanding in the search.

Before:

The text color of the search was red, which may make users think there was an error in the search.

After:

Highlighted the search text in green color to avoid misunderstanding.
Increased the font size and weight for readability.

• Change in CHANGELOG.md described in a way that is understandable for the average user (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 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.

I would like to know what you think about the fix. Any comments would be appreciated.

[ThiloteE]

Please check readability and provide screenshots for dark mode.

Please use a complementary colour scheme for the fix to create strong contrast. See here: https://en.wikipedia.org/wiki/Complementary_colors

But keep in mind, there are people that have a hard time distinguishing colours: impaired colour vision "Red–green color blindness is the most common form, followed by blue–yellow color blindness and total color blindness.[2]".

[u7232539]

Adopted high-contrast colors for text.
Avoided the combination of red-green and blue-yellow.
The background color is yellow (#ffff00) and the font color is purple (#7800A9).

In light theme:

In dark theme:

[ThiloteE]

Thank you, looking good!

[Siedlerchr]

Can you please adjust the changelog then (and it seems your latest changes are not yet pushed?)

[u7232539]

Sorry about that, I just pushed the latest changes.