G104 now raises an issue in case of reassignment err variable without checking

[TimonOmsk]

This PR is related to #891 issue

Now the G104 also checks for reassignments by checking referrers of err variable.

An issue will be raised only in case if no other expression related to the err variable exists:

This check was made using SSA(https://pkg.go.dev/golang.org/x/tools/go/ssa)

[codecov-commenter]

Codecov Report

Base: 74.37% // Head: 74.23% // Decreases project coverage by -0.13% ⚠️

Coverage data is based on head (049b036) compared to base (a0b7ebb).
Patch coverage: 57.69% of modified lines in pull request are covered.

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #895      +/-   ##
==========================================
- Coverage   74.37%   74.23%   -0.14%     
==========================================
  Files          51       51              
  Lines        3180     3206      +26     
==========================================
+ Hits         2365     2380      +15     
- Misses        746      757      +11     
  Partials       69       69              

Impacted Files	Coverage Δ
cmd/gosec/main.go	0.00% <0.00%> (ø)
helpers.go	42.07% <0.00%> (-1.12%)	⬇️
analyzer.go	89.72% <100.00%> (+0.25%)	⬆️
rules/errors.go	96.10% <100.00%> (+0.38%)	⬆️

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[TimonOmsk]

Closed because SSA requires complete program to build SSA, but gosec builds package by package and imports cannot be resolved.