fix(TypeAnalysis): remove duplicated brackets from printed solution

[mzacho]

When performing a type analysis and inspecting the log of the unclosed solution, it seems like the brackets ⟦⟧ for type variables belonging to expressions/ identifiers are duplicated on the left-side of the equation.

Example:

Typechecking the following program foo.tip

main() {
  var p;
  p = alloc null;
  *p = p;
  return 42;
}

with

"args": ["-types", "-verbose", "./examples/foo.tip"]

yields

[info] Processing foo.tip
[verbose] Parsing
[verbose] Declaration analysis
[verbose] Starting TypeAnalysis
[verbose] Visiting AProgram at 1:1
[verbose] Generating constraint ⟦42[5:10]⟧ = int
[verbose] Unifying ⟦42[5:10]⟧ and int
[verbose] Visiting AFunDeclaration at 1:1
[verbose] Generating constraint ⟦main(){...}:1:1⟧ = () -> ⟦42[5:10]⟧
[verbose] Unifying ⟦main(){...}:1:1⟧ and () -> ⟦42[5:10]⟧
[verbose] Visiting AFunBlockStmt at 1:8
[verbose] Visiting AVarStmt at 2:3
[verbose] Visiting AIdentifierDeclaration at 2:7
[verbose] Visiting AAssignStmt at 3:3
[verbose] Generating constraint ⟦p[2:7]⟧ = ⟦alloc null[3:7]⟧
[verbose] Unifying ⟦p[2:7]⟧ and ⟦alloc null[3:7]⟧
[verbose] Visiting AIdentifier at 3:3
[verbose] Visiting AAlloc at 3:7
[verbose] Generating constraint ⟦alloc null[3:7]⟧ = ⭡⟦null[3:13]⟧
[verbose] Unifying ⟦alloc null[3:7]⟧ and ⭡⟦null[3:13]⟧
[verbose] Visiting ANull at 3:13
[verbose] Generating constraint ⟦null[3:13]⟧ = ⭡x1
[verbose] Unifying ⟦null[3:13]⟧ and ⭡x1
[verbose] Visiting AAssignStmt at 4:3
[verbose] Generating constraint ⟦p[2:7]⟧ = ⭡⟦p[2:7]⟧
[verbose] Unifying ⟦p[2:7]⟧ and ⭡⟦p[2:7]⟧
[verbose] Unifying subterms ⟦null[3:13]⟧ and ⟦p[2:7]⟧
[verbose] Unifying ⟦null[3:13]⟧ and ⟦p[2:7]⟧
[verbose] Unifying subterms x1 and ⟦p[2:7]⟧
[verbose] Unifying x1 and ⟦p[2:7]⟧
[verbose] Visiting AIdentifier at 4:4
[verbose] Visiting AIdentifier at 4:8
[verbose] Visiting AReturnStmt at 5:3
[verbose] Visiting ANumber at 5:10
[verbose] Generating constraint ⟦42[5:10]⟧ = int
[verbose] Unifying ⟦42[5:10]⟧ and int
[info] Solution (not yet closed):
  ⟦x1⟧ = ⭡⟦p[2:7]⟧
  ⟦⟦p[2:7]⟧⟧ = ⭡⟦p[2:7]⟧
  ⟦⟦alloc null[3:7]⟧⟧ = ⭡⟦p[2:7]⟧
  ⟦⟦42[5:10]⟧⟧ = int
  ⟦⟦main(){...}:1:1⟧⟧ = () -> ⟦42[5:10]⟧
  ⟦⟦null[3:13]⟧⟧ = ⭡⟦p[2:7]⟧
[info] Inferred types:
  ⟦null[3:13]⟧ = ⭡μx2.⭡x2
  ⟦p[2:7]⟧ = μx2.⭡x2
  ⟦main(){...}:1:1⟧ = () -> int
  ⟦alloc null[3:7]⟧ = ⭡μx2.⭡x2
  ⟦42[5:10]⟧ = int
[info] Results of types analysis of ./examples/foo.tip written to ./out/foo.tip__types.ttip

before the fix and

...
[info] Solution (not yet closed):
  x1 = ⭡⟦p[2:7]⟧
  ⟦p[2:7]⟧ = ⭡⟦p[2:7]⟧
  ⟦alloc null[3:7]⟧ = ⭡⟦p[2:7]⟧
  ⟦42[5:10]⟧ = int
  ⟦main(){...}:1:1⟧ = () -> ⟦42[5:10]⟧
  ⟦null[3:13]⟧ = ⭡⟦p[2:7]⟧
...

after the fix.