feat(rules): `heading-level` supports sectioning roots

Currently only `dialog` and `role="dialog"` creates a new sectioning root.

fixes #92
12 jobs for bugfix/issue-92-role-dialog in 10 minutes and 55 seconds (queued for 2 seconds)
Status Job ID Name Coverage
  Prepare
passed #977889626
NPM

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  Build
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Build

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  Test
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Changelog

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Docs

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ESLint

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Jest

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98.02%
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Prettier

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license_scanning

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  Compatibility
passed #977889649
Node 10.x (LTS)

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passed #977889651
Node 12.x (LTS)

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Node 14.x (LTS)

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passed #977889661
Node 15.x (current)

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