Is your feature request related to a problem? Please describe.
We identified a legacy document method to copy text to the clipboard in #6912 and realized we don't currently lint for deprecated code.

Describe the solution you'd like
We would like to add ESLint-plugin-deprecation to warn (could also error) on deprecated code. It'd help us identify areas for improvement and keep EUI current with browsers.

The project has two dependencies, both of which are already in the EUI package.json file:

• @typescript-eslint/parser
• typescript