Add genesis export/init for marker deny send lists

[nullpointer0x00]

Description

closes: #1660

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Before we can merge this PR, please make sure that all the following items have been
checked off. If any of the checklist items are not applicable, please leave them but
write a little note why.

• Targeted PR against correct branch (see CONTRIBUTING.md)
• Linked to Github issue with discussion and accepted design OR link to spec that describes this work.
• Wrote unit and integration tests
• Updated relevant documentation (docs/) or specification (x/<module>/spec/)
• Added relevant godoc comments.
• Added a relevant changelog entry to the Unreleased section in CHANGELOG.md
• Re-reviewed Files changed in the Github PR explorer
• Review Codecov Report in the comment section below once CI passes

[codecov]

Codecov Report

Merging #1662 (ebbdd7a) into main (8556cd6) will decrease coverage by 0.02%.
The diff coverage is 60.31%.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1662      +/-   ##
==========================================
- Coverage   64.78%   64.77%   -0.02%     
==========================================
  Files         261      261              
  Lines       31249    31306      +57     
==========================================
+ Hits        20246    20279      +33     
- Misses       9724     9746      +22     
- Partials     1279     1281       +2     

Files Changed	Coverage Δ
x/marker/keeper/genesis.go	7.22% <0.00%> (-1.35%)	⬇️
x/marker/keeper/keeper.go	75.00% <0.00%> (-4.42%)	⬇️
x/marker/simulation/operations.go	79.47% <89.65%> (+0.63%)	⬆️
x/marker/types/genesis.go	40.74% <100.00%> (+2.27%)	⬆️
x/marker/types/key.go	82.14% <100.00%> (+4.87%)	⬆️

[Taztingo]

LGTM