[Improvement]: Enable strict Typescript

[jordisala1991]

It is recommended using strict mode of Typescript.

It allows to catch bugs on typings, and avoids use of any around the code.

[jordisala1991]

You can enable those checks one by one:

"noImplicitAny": true,
"noImplicitThis": true,
"alwaysStrict": true,
"strictBindCallApply": true,
"strictNullChecks": true,
"strictFunctionTypes": true,
"strictPropertyInitialization": true

Or with the strict flag:

"strict": true

Since the project is big enough, it should be enabled step by step, to avoid huge PRs.

[jordisala1991]

we are only missing:

"noImplicitAny": true,