MESH-2091/add-parent-child-map

[HenriqueNogara]

changelog

modified API

• Adds ChildDid storage, which tracks all child identities of a given parent identity;

data migration

• initializes the ChildDid storage;

[codecov]

Codecov Report

Merging #1568 (cfe622d) into develop (804fe85) will increase coverage by 0.13%.
The diff coverage is 44.44%.

Additional details and impacted files

@@             Coverage Diff             @@
##           develop    #1568      +/-   ##
===========================================
+ Coverage    58.53%   58.67%   +0.13%     
===========================================
  Files          142      142              
  Lines        32283    32236      -47     
===========================================
+ Hits         18898    18914      +16     
+ Misses       13385    13322      -63     

Files	Coverage Δ
pallets/identity/src/keys.rs	86.51% <100.00%> (-0.22%)	⬇️
pallets/identity/src/lib.rs	25.49% <33.33%> (+3.44%)	⬆️

... and 2 files with indirect coverage changes