Adds while expressions

[baszalmstra]

This PR adds while expressions to Mun.

The following code should work properly.

fn fibonacci(n:int):int {
    let a = 0;
    let b = 1;
    let i = 1;
    while i <= n {
        let sum = a + b;
        a = b;
        b = sum;
        i += 1;
    };
    a
}

• Implement parsing of while expressions.
• Implement proper type inferencing and diagnostics
  • Do not allow break expression with values inside while
• Implement code generation for the while statement

Depends on #62

[codecov]

Codecov Report

Merging #63 into master will increase coverage by 0.21%.
The diff coverage is 84.09%.

@@            Coverage Diff             @@
##           master      #63      +/-   ##
==========================================
+ Coverage   71.34%   71.55%   +0.21%     
==========================================
  Files         106      106              
  Lines        7073     7203     +130     
==========================================
+ Hits         5046     5154     +108     
- Misses       2027     2049      +22

Impacted Files	Coverage Δ
...ates/mun_syntax/src/parsing/grammar/expressions.rs	94.85% <100%> (+0.22%)	⬆️
crates/mun_syntax/src/syntax_kind/generated.rs	79.45% <100%> (+0.11%)	⬆️
crates/mun_runtime/src/test.rs	96% <100%> (+0.23%)	⬆️
crates/mun_syntax/src/tests/parser.rs	98.24% <100%> (+0.09%)	⬆️
crates/mun_hir/src/ty/tests.rs	96.03% <100%> (+0.12%)	⬆️
crates/mun_codegen/src/test.rs	100% <100%> (ø)	⬆️
crates/mun_hir/src/diagnostics.rs	16.45% <20%> (+0.23%)	⬆️
crates/mun_syntax/src/ast/generated.rs	56.45% <66.66%> (+0.28%)	⬆️
crates/mun_hir/src/expr.rs	76.76% <82.6%> (+0.7%)	⬆️
crates/mun_hir/src/ty/infer.rs	77.42% <94.28%> (+0.46%)	⬆️
... and 5 more

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 103c621...6160d84. Read the comment docs.

[baszalmstra]

While statements