[Update] Supports new features for the upcoming network reset.

[d0cd]

This PR,

• adds support for self.signer
• fixes code generation for mapping declarations
• fixes code generation for finalize blocks
• fixes code generation for external calls.

[codecov]

Codecov Report

Merging #2626 (67cdc56) into testnet3 (e820f7f) will decrease coverage by 0.51%.
The diff coverage is 52.11%.

@@             Coverage Diff              @@
##           testnet3    #2626      +/-   ##
============================================
- Coverage     80.03%   79.53%   -0.51%     
============================================
  Files           159      159              
  Lines          5395     5478      +83     
  Branches       5395     5478      +83     
============================================
+ Hits           4318     4357      +39     
- Misses         1077     1121      +44     

Files	Coverage Δ
compiler/ast/src/program/mod.rs	100.00% <ø> (ø)
compiler/compiler/src/compiler.rs	86.66% <ø> (ø)
compiler/compiler/tests/execute.rs	90.62% <100.00%> (+0.30%)	⬆️
compiler/compiler/tests/utilities/mod.rs	90.47% <100.00%> (ø)
compiler/parser/src/parser/file.rs	73.37% <100.00%> (ø)
compiler/passes/src/code_generation/generator.rs	75.00% <100.00%> (ø)
compiler/passes/src/code_generation/mod.rs	100.00% <100.00%> (ø)
compiler/span/src/symbol.rs	83.33% <ø> (ø)
...rors/src/errors/type_checker/type_checker_error.rs	76.35% <100.00%> (ø)
...iler/passes/src/type_checking/check_expressions.rs	81.81% <0.00%> (-0.60%)	⬇️
... and 3 more

... and 11 files with indirect coverage changes

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[bendyarm]

LGTM