gno lint should provide warnings for exported global variables

[moul]

While there might be instances where allowing this behavior is justified, incorporating a mechanism to disable the warning could prove beneficial.

For instance, introducing a // nolint comment to selectively suppress the warning could enhance flexibility in code analysis.

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This should warn:

var MyVar int

This shouldn't:

var MyVar int // nolint

[moul]

Should be extended with exported Const containing mutable fields like arrays.