Rename eth2 packages

[spacesailor24]

Description

Renames the packages:

• web3-eth2-core to web3-eth2-base
• web3-eth2-beaconchain to web3-eth2-beacon

Type of change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)

Checklist:

• I have selected the correct base branch.
• I have performed a self-review of my own code.
• I have commented my code, particularly in hard-to-understand areas.
• I have made corresponding changes to the documentation.
• My changes generate no new warnings.
• Any dependent changes have been merged and published in downstream modules.
• I ran npm run dtslint with success and extended the tests and types if necessary.
• I ran npm run test:unit with success.
• I ran npm run test:cov and my test cases cover all the lines and branches of the added code.
• I ran npm run build and tested dist/web3.min.js in a browser.
• I have tested my code on the live network.
• I have checked the Deploy Preview and it looks correct.
• I have updated the CHANGELOG.md file in the root folder.

[frankiebee]

looks good just waiting for tests to pass

[coveralls]

Coverage remained the same at 80.423% when pulling 59ffd01 on wyatt/rename-eth2-packages into 942161c on 1.x.

[GregTheGreek]

@spacesailor24 linter issues