chore: move `eslint`, `prettier` and `jest` configuration within `package.json`

[SauravMaheshkar]

Changes proposed by this PR can be summarised as follows :-

• Move the content from .prettierrc under the prettier key in package.json. Source(prettier docs)
• Move the content from .eslintrc.js under the eslintConfig key in package.json. Source(eslint docs)
• Move the content from jest.config.js under the jest key in package.json. Source(jest docs)

[coveralls]

Pull Request Test Coverage Report for Build 4708302913

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 44.741%

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Totals
Change from base Build 4660667751:	0.0%
Covered Lines:	254
Relevant Lines:	514

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💛 - Coveralls