Use npm instead of Yarn

[alanorth]

References

• Fixes https://github.com/DSpace/dspace-angular/issues/1074

Description

Simplify the project by using npm (which ships with Node.js) instead of Yarn (an extra global dependency and prerequisite).

The original reasons for using Yarn (dependency install speed and robust lockfiles) are no longer as compelling. In the past few years npm has improved in both of these areas. Furthermore, we are using Yarn 1.x "classic", which has been deprecated for several years and migration to Yarn 2, which is not backwards compatible, will require us to do some work anyway.

Instructions for Reviewers

Please add a more detailed description of the changes made by your PR. At a minimum, providing a bulleted list of changes in your PR is helpful to reviewers.

List of changes in this PR:

• Remove yarn.lock
• Update package.json to use npm run for all scripts
• Add package-lock.json

TODO:

• Update README.md with new instructions for npm
• Update CI and GitHub templates

Include guidance for how to test or review your PR.

Try installing dependencies and building the application in dev and production mode:

$ rm -rf node_modules && npm install --legacy-peer-deps
$ npm run build
$ npm start

Checklist

This checklist provides a reminder of what we are going to look for when reviewing your PR. You need not complete this checklist prior to creating your PR (draft PRs are always welcome). However, reviewers may request that you complete any actions in this list if you have not done so. If you are unsure about an item in the checklist, don't hesitate to ask. We're here to help!

• [x] My PR is small in size (e.g. less than 1,000 lines of code, not including comments & specs/tests), or I have provided reasons as to why that's not possible.
• [x] My PR passes ESLint validation using yarn lint
• [x] My PR doesn't introduce circular dependencies (verified via yarn check-circ-deps)
• [x] My PR includes TypeDoc comments for all new (or modified) public methods and classes. It also includes TypeDoc for large or complex private methods.
• [x] My PR passes all specs/tests and includes new/updated specs or tests based on the Code Testing Guide.
• [x] My PR aligns with Accessibility guidelines if it makes changes to the user interface.
• [x] My PR uses i18n (internationalization) keys instead of hardcoded English text, to allow for translations.
• [x] My PR includes details on how to test it. I've provided clear instructions to reviewers on how to successfully test this fix or feature.
• [x] If my PR includes new libraries/dependencies (in package.json), I've made sure their licenses align with the DSpace BSD License based on the Licensing of Contributions documentation.
• [x] If my PR includes new features or configurations, I've provided basic technical documentation in the PR itself.
• [x] If my PR fixes an issue ticket, I've linked them together.