Fix NPE when opening a non existing file from the recent files menu

[Siedlerchr]

Fixes #5334

dialogService object was null, because the FileHistoryMenu class is initialized before the ctor of JabRef frame creates the dialog service object

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• Change in CHANGELOG.md described
• Tests created for changes
• Manually tested changed features in running JabRef
• Screenshots added in PR description (for bigger UI changes)
• Ensured that the git commit message is a good one
• Check documentation status (Issue created for outdated help page at help.jabref.org?)

[tobiasdiez]

What about moving the initialization

jabref/src/main/java/org/jabref/gui/JabRefFrame.java

Line 146 in db96f88

private final FileHistoryMenu fileHistory = new FileHistoryMenu(prefs, this);

to the constructor JabRefFrame (and in addition making the dialogservice an constructor argument of filehistorymenu)?