Hoist shared dev tooling (mocha, semantic-release, typedoc) to root devDependencies #208

The same dev tooling versions (mocha, semantic-release, typedoc, typedoc-plugin-markdown, typedoc-plugin-merge-modules) are declared separately in the devDependencies of packages/core, packages/dom, packages/native, packages/sinon and examples/mocha. Every upgrade has to be hand-edited in each one, and the versions can drift apart.

Raised in review of #202: #202 (comment)

Proposal

Hoist these shared dev tools to the root package.json devDependencies, so an upgrade is a single edit.

Acceptance criteria

• mocha, semantic-release and the typedoc* packages are declared once, in the root devDependencies, and removed from the workspace packages
• yarn build, yarn docs, yarn compile, yarn lint and yarn test pass with the same test counts
• No published package's runtime dependencies change