dark mode: add edge modal

[sim51]

Scenario

• enable the dark mode (click on the gephi logo, and then select the dark mode in the top-right of the modal)
• load a graph
• on the right panel, click on the "Create new edge" button

Actual behavior

Selects are in light mode :

Expected behavior

Selects should be in dark

[Einithorynque]

The fields border should be gray as the adjacent fields.