Old benchmark loop should be detected

[pierrre]

Describe the bug
Benchmark loop using the old syntax for i := 0; i < b.N; i++ should be detected.

To Reproduce
Write a benchmark loop with for i := 0; i < b.N; i++ .

Expected behavior
The linter should suggest to rewrite to for range b.N

Additional context
Related to #13

[pierrre]

#13 (comment)

I think the proper solution here is to expose a setting to exclude patterns.

What kind of pattern do you have in mind ?
Do you want to match b.N or the entire line ?

[ckaznocha]

I was thinking the whole for statement (sans body) but I'm really not settled one way or another, do you have opinions?

[pierrre]

I was thinking the whole for statement (sans body)

looks good 👍