Path aliases and User Provider

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Solves #24 but while working on that, decided to separate User Provider logic.

The current PR is large but it will help to work with the user in the future.
What's implemented:

Paths

• create a craco.config file and prepare structure for further imports (Create React App Configuration Override for paths aliases) - did not work otherwise.
  The project can be further structured to have pages and components separately in src folder.

User Provider

• Refactor App.js - it is now easy to read
• Create a separate folder for UserProvider, with types and correct structure, keeping the same logic/comments from App.js to refactor further when needed,
• User Provider consolidation - remove prop drilling from other components, separate logic.
• Create MockUserProvider to enable testing demoUser

Other files

• Changed types in useLocalStorage - this would need further refactor, put the types as-is for now,
• Add correct types to some files connected to UserProvider

[evengene]

@nathanrydel please let me know if we can use this PR as-is or if you need me to create any additional issues.
I did not intent to refactor this much initially. 🙈 But to solve all the errors I had - this is the scope I came to.

While doing that, more ideas for tasks:

• Set linter settings to use potentially (while the project is small relatively - it will be easier to lint at this stage rather than later),
• Implement Redux/RTX for state and requests handling,
• Develop design

[evengene]

the branch is up-to-date with the main