[BUG] Fix cosmetic issues

[Aircoookie]

Some UI is not consistent. Fix before initial release.

• [x] submit/cancel buttons sometimes use <button>, sometimes <a>. Make sure they are styled consistently. Some buttons are taller than others.
• [x] Devices use an Update button to edit their details. This should be made consistent with the Edit button in the PKI section (e.g. for Domain Profiles, which also avoids possible confusion about this being a firmware or certificate update functionality for devices.
• [ ] It is possible that we want to use the entire main width for some elements, but form elements should be limited to a sane width.
• [x] Delete selected button uses secondary color for devices and primary for PKI. Use the same color everywhere (even better would be to visually disable the button if no entries are checked for bulk deletion)
• [x] Editing a domain profile uses the same template/strings as adding a new domain profile
• [x] tp-card-header div is taller if there is an action button, this may be personal preference, but this may be better consistently taller.

[AlexHx8472]

Regarding the tables in general. My suggestion would be to get rid of django-tables2 and do it manually with the build in features of django including pagination in the long term (using a ListView). As far as I understand tables2 is not that active in regards to development and we would get rid of another dependency, especially in the context of the future CRA issue. If you guys agree, we could use this to rework the styles of the card and the whole table appropriately.

[Aircoookie]

I agree we don't necessarily require django-tables2 to generate our tables. The only major feature we would need to replace with a custom implementation is sort-by-column, which boils down to using order_by on the queryset.

[AlexHx8472]

Yes, and since we will need to manipulate the queryset anyway for searching the table contents, this shouldn't be much of an issue. Most work will likely be adding styled links to the column headers, that should basically be it.