feat: add `src` route for all base smart contracts

[luislucena16]

• the objective is to aggregate src to modularise the files in a hierarchical order.

@0xneves please assign this to me!

[0xneves]

Yoo @luislucena16

It's not much of a practice to create src folder following hardhat standards, as some features already have hardcoded paths to test, scripts and contracts folders.

I'll close this issue as it doesn't fit the current schedule.

[luislucena16]

hey @0xneves I understand what you are saying, I think I didn't explain myself very well! What I mean is to add src inside contracts, where there are different contracts but inside src are the main ones, for example:

All this inside contracts:

- contracts:
   src: Swaplace.sol, SwaplaceFactory.sol
   mock: SwaplaceMock.sol 
   examples: SwaplaceExamples.sol
   poc: SwaplacePoC.sol

for me it's more modular and clearer!