feat: initialize fswap module

[170210]

Description

initialize fswap module

• make proto file
• prepare module template

Motivation and context

How has this been tested?

Screenshots (if appropriate):

Checklist:

• I followed the contributing guidelines and code of conduct.
• I have added a relevant changelog to CHANGELOG.md
• I have added tests to cover my changes.
• I have updated the documentation accordingly.
• I have updated API documentation client/docs/swagger-ui/swagger.yaml

[170210]

Is it necessary to update CHANGLOG.md

[jaeseung-bae]

Is it necessary to update CHANGLOG.md

I'm not sure.
I think, It's okay to update changelog once when we launch this module to main branch.

[codecov]

Codecov Report

Attention: Patch coverage is 14.10256% with 67 lines in your changes are missing coverage. Please review.

Project coverage is 70.30%. Comparing base (55b6566) to head (fea7a93).

Additional details and impacted files

@@            Coverage Diff             @@
##            pjdp1    #1336      +/-   ##
==========================================
- Coverage   70.38%   70.30%   -0.08%     
==========================================
  Files         643      654      +11     
  Lines       54793    54871      +78     
==========================================
+ Hits        38564    38575      +11     
- Misses      14054    14121      +67     
  Partials     2175     2175              

Files	Coverage Δ
x/fswap/types/genesis.go	100.00% <100.00%> (ø)
x/fswap/types/keys.go	0.00% <0.00%> (ø)
x/fswap/keeper/params.go	0.00% <0.00%> (ø)
x/fswap/types/codec.go	0.00% <0.00%> (ø)
x/fswap/types/params.go	66.66% <66.66%> (ø)
x/fswap/handler.go	0.00% <0.00%> (ø)
x/fswap/keeper/grpc_query.go	0.00% <0.00%> (ø)
x/fswap/genesis.go	0.00% <0.00%> (ø)
x/fswap/keeper/msg_server.go	0.00% <0.00%> (ø)
x/fswap/keeper/keeper.go	0.00% <0.00%> (ø)
... and 1 more

[170210]

Please ignore codecov, this is just a initial template.

[170210]

Should I remove this part. I think it should be init in genesis.go, because this is calculated by the current fnsa amounts.

finschia-sdk/proto/lbm/fswap/v1/params.proto

Lines 13 to 15 in 65b25b8

	// upper limit in new coin that this module can swap
	cosmos.base.v1beta1.Coin new_coin_swap_total_limit = 1
	[(gogoproto.nullable) = false, (gogoproto.castrepeated) = "github.com/Finschia/finschia-sdk/types.Coin"];

[zemyblue]

Can we query the swap rate?

[170210]

I heard that it is a constant value. Should we make a query for it? If it is needed, I think we can add it to the following query.

finschia-sdk/proto/lbm/fswap/v1/query.proto

Lines 25 to 29 in 4e0771a

	message QueryTotalSwappableAmountRequest {}
	message QueryTotalSwappableAmountResponse {
	cosmos.base.v1beta1.Coin swappable_new_coin_amount = 1
	[(gogoproto.nullable) = false, (gogoproto.castrepeated) = "github.com/Finschia/finschia-sdk/types.Coin"];
	}