Allow images to be shown in the tab titles

[LiamPClancy]

Is your feature request related to a problem? Please describe.
Not a issue just additional functionality.

Describe the solution you'd like
Essentially i'd like to be able to display images in the title section of a tab, i'd like to be able to also control if the image + Title, just image or just title were shown.

i'm considering adding something like

fn title_image(&mut self, _tab: &mut Self::Tab, _ui: &mut Ui) -> Option<Image>:

to the TabViewer trait returning null as default.
if Null - behave as is
if not null - show the image to the left of the text in the title.

Describe alternatives you've considered
Also considered passing in having the proposed title_image method return Option<&RetainedImage> but this would require the egui_extras crate which is unnecessary and would make it a bit opinionated.

Additional context
Happy to make a PR if this is something you're interested in?

[Adanos020]

This would be a very nice addition. I think tabs should support 3 variants:

• Title text only
• Image only
• Image and title text

Images should also be appropriately resized not to exceed the tab height.

[LiamPClancy]

wondering how you'd prefer this was acheived.

thinking of changing the title trait method to accept an enum

something like

enum TabTitle{
      Title(String), 
      Image(Image, String)
      }

The if the user wanted to have title and string, it'd be provided in the Image variant.
If not provided it could continue with the default title that is currently used?

alternatively, could add the additional method as mentioned in the initial comment, and if both title and image methods return values both will be used?

also happy with a different approach if you have a different preference?

[Adanos020]

I'd imagine the enum looking something like

enum TabTitle {
    Text(String),
    Image(Image),
    ImageAndText(Image, String),
}

[RegenJacob]

It might be nice to also allow egui's RichText for tab titles