fixed the compiler panicking when a break is outside of a loop

[trocher]

What I did

Fixed #3176

How I did it

Removed vy.ast.Break from ignored_types in FunctionNodeVisitor and created a function Visit_Break that behave similarly to visit_Continue to check that the break statement is enclosed in a loop.

How to verify it

Compiling the following contract will now output vyper.exceptions.StructureException: `break` must be enclosed in a `for` loop instead of the compiler panicking.

@external
def foo():
    break

Commit message

fix: improve error message for break statement outside of a loop

Description for the changelog

Improve error message for break statement outside of a loop

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[codecov-commenter]

Codecov Report

Merging #3177 (20410c0) into master (ac2fa14) will increase coverage by 0.00%.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##           master    #3177   +/-   ##
=======================================
  Coverage   88.48%   88.48%           
=======================================
  Files          85       85           
  Lines       10756    10760    +4     
  Branches     2286     2287    +1     
=======================================
+ Hits         9517     9521    +4     
  Misses        789      789           
  Partials      450      450           

Impacted Files	Coverage Δ
vyper/semantics/analysis/local.py	91.21% <100.00%> (+0.10%)	⬆️

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[fubuloubu]

Good work! Can we add a test showing the compiler successfully throws under this scenario?