Add an Add and Delete tree ranks option

[acwhite211]

Fixes #598

Checklist

• Self-review the PR after opening it to make sure the changes look good
  and self-explanatory (or properly documented)
• Add relevant issue to release milestone

Testing instructions

• Open a tree

• Click on the plus icon in the header, located between the pencil and the first rank (Planet | Earth | Root | ...)

• Choose a parent rank

• Click continue

• Define the proprieties of your new rank

• save

• verify that the new node has been added into the tree ranks

• Open a tree

• Click on the pencil icon in the header, located at the front of the headers, before the first rank (Planet | Earth | Root | ...)

• Click on a pencil next to a tree rank

• Click delete

• Confirm deletion

• verify that the new node has been deleted from the tree ranks

[maxpatiiuk]

excited to finally have this coming to sp7!
just hoping there isn't some dark magic/special logic going on in sp6 that we may be missing here

[maxpatiiuk]

back-end endpoints are overcomplicated

[emenslin]

Testing instructions

• Open a tree

• Click on the plus icon in the header, located between the pencil and the first rank (Planet | Earth | Root | ...)

• Choose a parent rank

• Click continue

• Define the proprieties of your new rank

• save

• verify that the new node has been added into the tree ranks

• Open a tree

• Click on the pencil icon in the header, located at the front of the headers, before the first rank (Planet | Earth | Root | ...)

• Click on a pencil next to a tree rank

• Click delete

• Confirm deletion

• verify that the new node has been deleted from the tree ranks

---

Deletion Blocker looks great!

Uja5aN07nf.mp4

[Areyes42]

Testing instructions

• Open a tree

• Click on the plus icon in the header, located between the pencil and the first rank (Planet | Earth | Root | ...)

• Choose a parent rank

• Click continue

• Define the proprieties of your new rank

• save

• verify that the new node has been added into the tree ranks

• Open a tree

• Click on the pencil icon in the header, located at the front of the headers, before the first rank (Planet | Earth | Root | ...)

• Click on a pencil next to a tree rank

• Click delete

• Confirm deletion

• verify that the new node has been deleted from the tree ranks

---

Adding and deleting works as expected and the deletion blocker shows up, great job!

[realVinayak]

just some minor changes, except the parent query. I don't personally think it is necessary (you can get the parent directly) so searching by name is redundant, Am i misunderstanding something?