[FIX] Fixes overflow in Administration panel

[aKn1ghtOut]

Checklist

• I have read the Contributing Guide
• I have signed the CLA
• Lint and unit tests pass locally with my changes
• I have added tests that prove my fix is effective or that my feature works (if applicable)
• I have added necessary documentation (if applicable)
• Any dependent changes have been merged and published in downstream modules

Issue(s)

Fixes issue #19939
In the administration panel sidebar, the last item is cut off because of overflow. This happens because the Header takes 60px of height(calculated), while the Sidebar.Content element below it has a maximum height of "100%". Hence, he content element expands to be equal to the height of the body, but the lat 60px of it are then cut-off, as the effective height of both the elements together becomes (100% + 60px)

Proposed changes

The Sidebar Header in the administration panel was shifted from outside the Sidebar.Content box to inside it. Now, the Content having a maximum height of 100% does not become a problem as it is the calculated height of both the content and the header together, and there is no overflow.

Steps to test or reproduce

• Login as Administrator.
• Go to the Administrator panel
• Scroll to the bottom of the sidebar [The last menu-item is cut-off]

[gabriellsh]

Hey @aKn1ghtOut thanks a lot for the help!

Unfortunately, your fix is not really a good way to do it, since the header should remain static while we scroll. We had recently introduced a new (js) scroll to rocket.chat, and the fix is a little different. You can take a look at my PR #19944 if you wanna see how I did. Anyway, thanks for your comprehension!

[aKn1ghtOut]

Thanks a lot for @gabriellsh. I did expect this, and to learn the right way of doing things here was most important. Did open the PR mostly because I was able to pinpoint the exact problem with a bit of time, so that could help someone to actually solve it faster! :)