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 - for electron tests, the packages are published to (and installed from) verdaccio using a very high canary version, but lerna doesn't update peer dependencies of packages when publishing, resulting in a conflict.

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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