Support the WithOffset method

[nunnatsa]

The linter used to ignore patterns like Expect(len(x)).WithOffset(1).Should(Equal3)). now the linter will catch these patterns as well.

Type of change

• [x] Bug fix (non-breaking change which fixes an issue)

How Has This Been Tested?

• [x] Added test case and related test data
• [x] Update the functional test

Checklist:

• [x] I have performed a self-review of my own code
• [x] My changes generate no new warnings
• [x] I have added tests that prove my fix is effective or that my feature works
• [x] New and existing unit tests pass locally with my changes
• [x] I ran golangci-lint

[coveralls]

Pull Request Test Coverage Report for Build 4466542229

• 19 of 59 (32.2%) changed or added relevant lines in 2 files are covered.
• 2 unchanged lines in 1 file lost coverage.
• Overall coverage decreased (-4.2%) to 82.526%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
gomegahandler/handler.go	2	42	4.76%
<!--	Total:	19	59	32.2%	-->

Files with Coverage Reduction	New Missed Lines	%
ginkgo_linter.go	2	88.42%
<!--	Total:	2		-->

Totals
Change from base Build 4401338548:	-4.2%
Covered Lines:	647
Relevant Lines:	784

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💛 - Coveralls