Impl RPCs to access Swap APIs

[zktony]

Describe your changes

Impl RPCs to access Swap APIs.

[Gauthamastro]

LGTM

[codecov]

Codecov Report

Attention: 19 lines in your changes are missing coverage. Please review.

Comparison is base (390523c) 37.49% compared to head (8ab6908) 37.30%.

❗ Current head 8ab6908 differs from pull request most recent head 973d921. Consider uploading reports for the commit 973d921 to get more accurate results

Files	Patch %	Lines
rpc/swap/src/lib.rs	0.00%	18 Missing ⚠️
nodes/mainnet/src/node_rpc.rs	0.00%	1 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##           Develop     #890      +/-   ##
===========================================
- Coverage    37.49%   37.30%   -0.19%     
===========================================
  Files           62       63       +1     
  Lines         3753     3772      +19     
===========================================
  Hits          1407     1407              
- Misses        2346     2365      +19     

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[zktony]

To use RPCs, use follwing commands:-
curl -H "Content-Type: application/json" -d '{"id":1, "jsonrpc":"2.0", "method": "tx_quotePriceExactTokensForTokens", "params": ["PDEX", "<AssetId>", <Amount>, true]}' http://localhost:9944/