Drop legacy peer dependencies

[yousif-bugsnag]

Goal

Drop legacy peer dependencies

Design

No longer required after dropping package-lock files from sub-packages and updating dependencies.

Changeset

remove use of --legacy-peer-deps flag in all build files (except the electron ci step), and remove the .npmrc file from the repo.

Removed all unnecessary unit-test related files and dependencies from the angular test fixture as these were causing conflicts and are not required for our tests.

legacy-peer-deps is still required in a couple of places:

• browser webpack3 test fixture - older version of webpack causes a conflict, so added a .npmrc with legacy-peer-deps=true to the test fixture directory
• Electron e2e tests - there still seems to be a dependency conflict when installing the packages from local verdaccio into the test fixture, so reinstated legacy-peer-deps in test/electron/features/support/app.js for now. I think this has to do with lockfiles in the packages, but will investigate/PR that separately to keep the PR size manageable

Testing

full ci build

[github-actions]

@bugsnag/browser bundle size diff

	Minified	Minfied + Gzipped
Before	45.76 kB	13.77 kB
After	45.76 kB	13.77 kB
±	No change	No change

code coverage diff

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