RFR: 7056: Fix dark mode [v3]

[Alex Macdonald]

On Thu, 18 Jan 2024 09:49:32 GMT, Brice Dutheil <bdutheil at openjdk.org> wrote:

>> This change allows a user of the JMC RCP application to switch the appearance with the default Eclipse themes.
>> 
>> Those are shipped via the `org.eclipse.ui.themes` and `org.eclipse.e4.ui.css.swt.theme` plugin.
>> In order to activate them all that is is required is to add the above in the application feature file, and to declare them in the application manifest file.
>> 
>> 
>> 
>> **After**
>> ![Screenshot 2022-01-16 at 16 23 46](https://user-images.githubusercontent.com/803621/149666554-3016effc-b527-4dd7-aa6b-baa07a9569ad.png)
>> ![Screenshot 2022-01-16 at 16 26 21](https://user-images.githubusercontent.com/803621/149666560-cab76fc9-dd9a-4977-9fe7-0a7dc99335c5.png)
>> 
>> 
>> 
>> **Before**
>> ![Screenshot 2022-01-16 at 16 24 45](https://user-images.githubusercontent.com/803621/149666542-b8e22717-a797-44b6-9805-30b9c14fb9fa.png)
>> There's no theme, as such the combo box doesn't open either.
>
> Brice Dutheil has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Bump copyright year to 2023

This will need a copyright bump to 2024 and can be integrated afterwards.

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PR Comment: https://git.openjdk.org/jmc/pull/362#issuecomment-1898784138