Use FormPage for Import Model page

[feloy]

What does this PR do?

Updtae the "Import Model" page to use the dedicated FormPage component instead of NavPage

Also change a few colors to support light mode (except colors in the form itself)

Screenshot / video of UI

What issues does this PR fix or reference?

Fixes #1229

How to test this PR?

Navigate to Catalog > Import

[axel7083]

One small issue

Before

dark	light

After

dark	light

We have a clear improvement on the light mode (nice job), but we loose the separation between the secondary navigation and the content on both theme

[axel7083]

I am wondering if we should not use var(--pd-invert-content-bg) as in the preferences, it is what is used however this would make the card of the form hidden :/

[feloy]

One small issue

[...]
We have a clear improvement on the light mode (nice job), but we loose the separation between the secondary navigation and the content on both theme

Do you mean the vertical shadow between the 2 zones? If so, this issue tracks the problem: containers/podman-desktop#7549

[axel7083]

Do you mean the vertical shadow between the 2 zones? If so, this issue tracks the problem:

Sorry if I was not clear enough, the fact that the main and secondary navigation are both the same color:

[feloy]

Do you mean the vertical shadow between the 2 zones? If so, this issue tracks the problem:

Sorry if I was not clear enough, the fact that the main and secondary navigation are both the same color:

I double-checked, and for me the 2 colors were already before really the same (#343434), but the shadow in the middle makes one think they are different