Site editor: Improve consistency of some of the navigation panel titles and controls

[afercia]

Description

As a user, when using the Site editor navigation panel, I would expect a few things to be more consistent. Specifically, some of the panel views titles could be more consistent and I'm not sure I understand why the 'add new' plus + button is not available on some of the views where it could be handy

A quick comparison:

Site editor > Templates

After the title 'Templates' there is a 'Add New Template' button that makes perfectly sense.
At the bottom ot the navigation panel a 'Manage all templates' button brings to the all templates view:

• As a user, I know I just clicked a control that says 'Manage'. However the title of the screen I get doesn't use the verb 'Manage' anywhere.
• The title of the panel is 'All templates'.
• The 'Add New Template' button disappeared. As a user, I would expect to find it in the same position within the navigation panel. Although there's another 'Add New Template' button at the top right of the list view, I'm not sure removing it from the navigation pane helps consistency and predictability. I'm not sure what's the reasoning behind that, whether there's some technical issue that prevents to show the 'Add New Template' button in the navigation panel sub-view, but I would consider to add it for better consistency.

Site editor > Pages

Similarly, there is a 'Draft a new page' button.

Clicking 'Manage all pages' brings to the sub view:

• The title is 'Pages'. I would expect it to be 'All pages', for consistency with the templates. Actually, two different levels of the panel have the same title 'Pages', which I would say is not ideal.
• No reference to the 'Manage' action anywhere. Note that the verb 'manage' is used in the upper level instead.
• The 'Draft a new page' button disappeared.

Site editor > Patterns > Manage all template parts

This is somehow a special case because to go to the template parts list, users have to go through the Patterns first, which is already confusing in the first place. Anyways:

There's a button that is labelled 'Create pattern'.
The button looks exactly like the 'Add New Template' and 'Draft a new page' buttons.
As a user, I would expect this button to work in the same way the other buttons do.
It is labelled 'Create pattern' so that as a user I'd expect that it only has one action: create a pattern.
Instead, the button opens a menu with three available actions:

• Create pattern
• Create template part
• Import pattern from JSON

I'm not sure this inconsistency helps the UI to be more intuitive and predictable. Controls that look similarly should work similarly.

Clicking 'Manage all template parts' brings to the sub view:

• The panel sub view title is 'All template parts', which is consistent with the templates sub view but it's not with the pages one.
• No reference to the 'Manage' action anywhere. Note that the verb 'manage' is used in the upper level instead.
• The 'plus' button disappeared

Overall, I think the design and consistency of these panel views and sub views could be improved.

Step-by-step reproduction instructions

See description above

Screenshots, screen recording, code snippet

No response

Environment info

No response

Please confirm that you have searched existing issues in the repo.

Yes

Please confirm that you have tested with all plugins deactivated except Gutenberg.

Yes