[Tracking] forc-client techincal debts

[kayagokalp]

forc-client is a very vibrant section of our codebase, and a lot of changes land there regularly, and it is getting expanded as the time pass. I think it is time for us to have a nice cleaning done, so that we have stronger foundations in place.

1. Let's try to de-duplicate efforst between sdk and forc-client as much as possible, now that sdk has a estimation flow in place we can remove our code and use theirs
2. Folder/file structure can be improved a little: forc-client is expanding all the time and some files can be split or could use same new names.
3. As part of feat: create and deploy a reference proxy contract for contracts with [proxy] enabled #6069 we have a nice improvement in testability of the crate, we should continue this effort and extend our test suite.
4. We should start following the code coverage for forc-client.
5. We can use indoc for most of the places we are embedding src code for better readability
6. https://github.com/FuelLabs/sway/pull/6250/files/11333a39d9e39f13ba77c6db577e40982c479a9e#r1712381927