Optimize tree loading

[didoda]

This provides an optimization on tree load data in 2 ways: performance (using cache and reducing total calls number) and UI.

This introduces 3 endpoints (that internally use cache):

• GET /tree/node/{id} (cache key is tree-node-<id>)
• GET /tree/parent/{id} (cache key is tree-parent-<id>)
• GET /tree/parents/{type}/{id} (cache key is tree-parents-<id>-<type>)

In UI, we have a message that tells what exactly it's loading in that moment: the user knows what's going on.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 99.68%. Comparing base (2e94951) to head (2ae73af).
Report is 1 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff            @@
##             master    #1094   +/-   ##
=========================================
  Coverage     99.68%   99.68%           
- Complexity     1186     1200   +14     
=========================================
  Files            93       93           
  Lines          4688     4782   +94     
=========================================
+ Hits           4673     4767   +94     
  Misses           15       15           

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