docs: unify storage overview docs

[hzxa21]

• Unify developer/component/storage.md and state-store-overview.md
• Remove developer folder

[codecov]

Codecov Report

Merging #1546 (e1f9bf7) into main (e91b0b2) will increase coverage by 0.00%.
The diff coverage is n/a.

@@            Coverage Diff            @@
##               main    #1546   +/-   ##
=========================================
  Coverage     69.61%   69.61%           
  Complexity     2766     2766           
=========================================
  Files          1035     1035           
  Lines         90891    90891           
  Branches       1790     1790           
=========================================
+ Hits          63270    63271    +1     
+ Misses        26730    26729    -1     
  Partials        891      891           

Flag	Coverage Δ
java	61.01% <ø> (ø)
rust	71.42% <ø> (+<0.01%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
rust/common/src/types/ordered_float.rs	23.50% <0.00%> (-0.20%)	⬇️
.../src/executor/managed_state/aggregation/extreme.rs	90.40% <0.00%> (+0.27%)	⬆️

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