feat: include echidna fuzz swap tests for native ether and ERC1155 asset

[0xneves]

Feature Request

Describe the Feature Request

The PR #218 introduces the tests with ERC1155 and PR #213 introduces unit tests on TestSwapFactory.test.ts and TestSwaplace.test.ts. Such unit tests don't exist in echidna for fuzzing.

Describe Preferred Solution

The files in question are TestSwaplace.sol and TestSwapFactory.sol in echidna folder.

The definition of done:

• [ ] Add tests that utilize native ether swaps sent by the swap owner in the TestSwaplace.sol file.
• [ ] Add tests that utilize native ether swaps sent by the swap aceptee in the TestSwaplace.sol file.
• [ ] Add tests that build ERC1155 assets in the TestSwapFactory.sol file
• [ ] Add tests for swaps that utilize ERC1155 assets in the TestSwaplace.sol file.