Update UI section in DG

[jessicax941]

• [x] update UI class diagram

• Toggle panel command

• [x] partial class diagram for side panels

• [x] update implementation for toggle panel command

• [x] update ToggleSequenceDiagram

• [x] update ToggleActivityDiagram

• Change font command

• [x] add ChangeFontSequenceDiagram

• [x] changeFont activity diagram

• [x] add implementation for change font

• Set dark/light theme

• [x] set dark/light theme implementation

• [x] set dark/light theme sequence diagram

• [x] set dark/light theme activity diagram

[Dandford]

Moved to 1.4