Implement a linter to check for the order of testing.TB parameter

A follow-up of !6183 (comment 1505963171)

This MR implements an analyzer to detect parameters of test helper functions. testing.TB arguments should always be passed as first parameter, followed by context.Context. This rule is noted in https://gitlab.com/gitlab-org/gitaly/-/blob/master/STYLE.md?ref_type=heads#test-helpers.

• Bad func testHelper(paramA string, t *testing.T)

• Bad func testHelper(ctx context.Context, t *testing.T)

• Bad func testHelper(t *testing.T, paramA string, ctx context.Context)

• Good func testHelper(t *testing.T)

• Good func testHelper(t *testing.T, ctx context.Context)

• Good func testHelper(t *testing.T, ctx context.Context, paramA string)