feat: allow user to choose build mode: debug (default) or release

[AlexD10S]

Allow user to indicate the build mode for the contract: debug (default) or release with the flag --release.

Example:

pop build contract -p ./my_contract --release

Closes #102

[codecov]

Codecov Report

Attention: Patch coverage is 0% with 8 lines in your changes missing coverage. Please review.

Project coverage is 56.52%. Comparing base (2713de5) to head (0d72ab1).
Report is 1 commits behind head on main.

@@            Coverage Diff             @@
##             main     #202      +/-   ##
==========================================
- Coverage   56.58%   56.52%   -0.07%     
==========================================
  Files          33       33              
  Lines        3513     3517       +4     
  Branches     3513     3517       +4     
==========================================
  Hits         1988     1988              
- Misses       1232     1236       +4     
  Partials      293      293              

Files	Coverage Δ
crates/pop-contracts/src/call.rs	0.00% <ø> (ø)
crates/pop-cli/src/commands/up/contract.rs	0.00% <0.00%> (ø)
crates/pop-cli/src/commands/build/contract.rs	0.00% <0.00%> (ø)
crates/pop-contracts/src/build.rs	0.00% <0.00%> (ø)