refactor(x/ecocredit): consistent amount and key field names

[ryanchristo]

Description

This pull request cleans up the following core and marketplace field names:

• SellOrder.AskPrice renamed to SellOrder.AskAmount ("price" is the denom and amount combined)
• SellOrderInfo.AskPrice renamed to SellOrderInfo.AskAmount ("price" is the denom and amount combined)
• SellOrder.BatchId renamed to SellOrder.BatchKey (followup from renaming internal id to key in core)
• Market.CreditType renamed to Market.CreditTypeAbbrev (followup from renaming credit type in core)
• BatchBalance.Tradable renamed to BatchBalance.TradableAmount (consistent with supply and send credits)
• BatchBalance.Retired renamed to BatchBalance.RetiredAmount (consistent with supply and send credits)
• BatchBalance.Escrowed renamed to BatchBalance.EscrowedAmount (consistent with tradable and retired)
• BatchBalanceInfo.Tradable renamed to BatchBalanceInfo.TradableAmount (consistent with supply and send credits)
• BatchBalanceInfo.Retired renamed to BatchBalanceInfo.RetiredAmount (consistent with supply and send credits)
• BatchBalanceInfo.Escrowed renamed to BatchBalanceInfo.EscrowedAmount (consistent with tradable and retired)

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Author Checklist

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I have...

• included the correct type prefix in the PR title
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I have...

• confirmed the correct type prefix in the PR title
• confirmed ! in the type prefix if API or client breaking change
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• reviewed state machine logic
• reviewed API design and naming
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[codecov]

Codecov Report

Merging #1123 (24f79a2) into master (852fb8d) will decrease coverage by 0.04%.
The diff coverage is 89.75%.

@@            Coverage Diff             @@
##           master    #1123      +/-   ##
==========================================
- Coverage   69.86%   69.82%   -0.05%     
==========================================
  Files         218      218              
  Lines       22243    22243              
==========================================
- Hits        15541    15531      -10     
- Misses       5365     5372       +7     
- Partials     1337     1340       +3     

Flag	Coverage Δ
experimental-codecov	69.66% <89.75%> (-0.10%)	⬇️
stable-codecov	64.17% <89.75%> (+0.07%)	⬆️

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[clevinson]

ack!