Integrate order sequence into new DEX events and order queries.

[dzmitryhil]

Description

Integrate order sequence into new DEX events and order queries.

• Integrate new DEX events with the min required info
• Add order sequence to all queries returning order(s)
• Update all required tests + add extra to test the events consistency
• Update genesis import/export to import/export current order sequence
• Update naming of the order sequence
• Describe DEX events in the spec.

Reviewers checklist:

• Try to write more meaningful comments with clear actions to be taken.
• Nit-picking should be unblocking. Focus on core issues.

Authors checklist

• Provide a concise and meaningful description
• Review the code yourself first, before making the PR.
• Annotate your PR in places that require explanation.
• Think and try to split the PR to smaller PR if it is big.

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This change is 

[codecov]

Codecov Report

Attention: Patch coverage is 85.84475% with 31 lines in your changes missing coverage. Please review.

Project coverage is 57.86%. Comparing base (5a00fe2) to head (fc94e4e).
Report is 23 commits behind head on master.

Files with missing lines	Patch %	Lines
x/dex/keeper/keeper.go	89.89%	3 Missing and 7 partials ⚠️
x/dex/genesis.go	65.21%	4 Missing and 4 partials ⚠️
x/dex/keeper/keeper_matching.go	73.91%	4 Missing and 2 partials ⚠️
x/dex/keeper/keeper_store.go	78.57%	2 Missing and 1 partial ⚠️
x/dex/keeper/keeper_good_til.go	88.23%	0 Missing and 2 partials ⚠️
x/dex/types/genesis.go	71.42%	1 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #1027      +/-   ##
==========================================
- Coverage   63.30%   57.86%   -5.44%     
==========================================
  Files         159      159              
  Lines       18308    18320      +12     
==========================================
- Hits        11590    10601     -989     
- Misses       5691     6736    +1045     
+ Partials     1027      983      -44     

Flag	Coverage Δ
coreum	57.86% <85.84%> (-0.01%)	⬇️
coreum-integration-tests-modules	0.00% <0.00%> (-53.31%)	⬇️

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[masihyeganeh]

Reviewed 30 of 30 files at r1, all commit messages.
Reviewable status: complete! all files reviewed, all discussions resolved (waiting on @miladz68 and @ysv)

[masihyeganeh]

Reviewed 1 of 1 files at r2, all commit messages.
Reviewable status: complete! all files reviewed, all discussions resolved (waiting on @miladz68 and @ysv)

[miladz68]

Reviewed 30 of 30 files at r1, 1 of 1 files at r2, all commit messages.
Reviewable status: complete! all files reviewed, all discussions resolved (waiting on @ysv)