[WIP] - Convert to v2 Addon

[cloke]

Converts to a v2 add-on. The test app builds and works, but still working through some of the ember-try scenarios.

Also switches to pnpm from yarn. This solved some babel errors that popped up and brings it more in line with the general ember add-on tooling.

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This pull request includes significant changes to the CI configuration, dependency management, and documentation. The most important changes include switching from Yarn to pnpm for dependency management, updating the CI workflow to cache dependencies and use pnpm, and removing extensive documentation and configuration files.

CI Configuration and Dependency Management:

• .github/workflows/ci.yml: Updated CI workflow to use pnpm instead of Yarn for installing dependencies, running lint, and executing tests. Added a new job to cache dependencies using pnpm. [1] [2] [3]
• CONTRIBUTING.md: Updated commands to use pnpm instead of Yarn for installing dependencies, linting, and running tests.

Documentation and Configuration Cleanup:

• .npmignore: Removed extensive list of files and directories to be ignored.
• docs/: Removed detailed documentation for did-intersect and scroll-into-view modifiers. [1] [2]
• ember-cli-build.js: Removed the build configuration file.

Miscellaneous:

• ember-scroll-modifiers/.eslintignore: Added new ignore patterns.
• ember-scroll-modifiers/.eslintrc.cjs: Added new ESLint configuration file.
• ember-scroll-modifiers/.gitignore: Updated ignore patterns.
• ember-scroll-modifiers/.prettierignore: Added new ignore patterns.
• ember-scroll-modifiers/.prettierrc.cjs: Renamed and updated Prettier configuration file.