test: integration tests, doc tests and improve coverage

[AlexD10S]

PR focused on improving the testing:

• Integration test to cover the entire parachain lifecycle: new (all the supported templates), build, up
• Integration test to cover the entire contract lifecycle: new (all the supported templates), build, up, call
  This 2 tasks closes test: integration test for complete contract process #218
• Flag skip_confirm to skip user confirmation in pop up parachain. Needed for integration tests, and closes Flag to skip user confirmation #208
• In CI, run integration tests for ubuntu and macOS.
• Fix crate documentation and ensure the tests pass:
  - To try in crates/pop_contracts run cargo test --doc
  - To try in crates/pop_parachains run cargo test --doc
• Add the check cargo test --doc in CI to ensure documentation is updated with code changes.
• Add some missing unit tests in the pop_contracts crate.
• Ensure the contracts node process is killed after the tests, solving an issue encountered when running the tests locally.

[codecov]

Codecov Report

Attention: Patch coverage is 61.33333% with 58 lines in your changes missing coverage. Please review.

Project coverage is 70.81%. Comparing base (70d3869) to head (b9e8d77).

@@            Coverage Diff             @@
##             main     #242      +/-   ##
==========================================
+ Coverage   70.46%   70.81%   +0.34%     
==========================================
  Files          47       47              
  Lines        7536     7664     +128     
  Branches     7536     7664     +128     
==========================================
+ Hits         5310     5427     +117     
+ Misses       1333     1315      -18     
- Partials      893      922      +29     

Files	Coverage Δ
crates/pop-contracts/src/errors.rs	0.00% <ø> (ø)
crates/pop-contracts/src/up.rs	77.65% <50.00%> (-0.05%)	⬇️
crates/pop-contracts/src/utils/contracts_node.rs	63.71% <42.85%> (+0.98%)	⬆️
crates/pop-contracts/src/utils/helpers.rs	81.81% <78.94%> (+3.09%)	⬆️
crates/pop-contracts/src/utils/signer.rs	84.37% <81.81%> (+44.37%)	⬆️
crates/pop-cli/src/commands/up/contract.rs	26.22% <0.00%> (-0.36%)	⬇️
crates/pop-contracts/src/call.rs	79.06% <74.64%> (+9.22%)	⬆️
crates/pop-cli/src/commands/up/parachain.rs	7.55% <0.00%> (-0.23%)	⬇️

... and 1 file with indirect coverage changes