tools: update ESLint to 5.0.0
This is still a work in progress. ESLint 5.x hasn't actually been released yet. This PR contains ESLint v5.0.0 v5.0.0-alpha.3 v5.0.0-rc.0. The two commits also need to be rebased in the opposite order to avoid a broken commit from being in master.
Checklist
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make -j4 test
(UNIX), orvcbuild test
(Windows) passes -
tests and/or benchmarks are included -
commit message follows commit guidelines