Add linting and formatting to repo

[marceljay]

The project should ideally have standardized rules for our code enforced via tooling.
This issue should serve as the initial discussion of these rules.

Here are some suggestions for tools to be used:

• JS/TS linting: ESLint
• Formatting: Prettier
• Solidity Linting: Solhint, Prettier Plugin for Solidity

Open Questions to be discussed (can be extended):

1. Which tools should we use?
2. What rules can we agree on? (One of the most important ones for now might be the printWidth (columns).

[marceljay]

Initial work has been done by PR: #377

[marceljay]

@asimpk @arthurka-o Do you have any input or a strategy on how we deal with the various "rules" applied in the different packages?

[arthurka-o]

Not really. I don't have a lot of experience in linters.
What do you mean by various "rules" applied in the different packages? Do you mean .eslintrc.json in every TS package?

[marceljay]

I meant that different packages do not seem to have the same rules (e.g. max-line-length) and thus depending on the rule, many issues will occur.

[arthurka-o]

Maybe we can set up the biggest value of all packages for every rule?