CI Update

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Currently, we are hitting the execution limit of 50 minutes in Travis, so removing the tests and using the coverage for checking the tests as well.

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Changes Introduced:

• Original Travis divided, and now only have coverage in it. (The current running time is at max 24 minutes)
• Github Actions is now being used for tests. (The current running time is at max 13 minutes)
• README updated to reflect the build status and test coverage.
• hardhat-docgen added to create technical documentation with inline coding (will perfectly fit with @computerphysicslab 's recent documentation task).
• Some prettier commands updated (write and check commands added).

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IMPORTANT: To speed up the CI, I am using npm ci instead of npm i, which makes use of package-lock.json.

Thus from now onwards, we should install all packages using npm, and not from yarn.