Feature/optional strict mode

[zoff4ick]

• tests and linter show no problems (npm t)
• tests are added/updated for bug fixes and new features
• code is properly formatted (npm run fmt)
• description of changes is added in CHANGELOG.md
• update .d.ts typings

[zoff4ick]

Hello. On our last Q&A meeting we discussed that it would be useful to have a strict mode in data collector. Exact question in the video (https://youtu.be/OuHazDcfh7k?si=Vqw-Rz8CWKy1po8y&t=6550) (link with timecode)

By default we can reassign values of keys as many times as we want (at least as long as collector has done === false). But sometimes we don't need an ability of reassigning values and we want to work with less mutable structures/collections to prevent some uncontrolled changes/mutations. So I implemented the optional key "allowReassignment" in the collector's options. So if we want want to disable mutation of values for already assigned keys (those whom already store values) we should pass allowReassignment: false to options.

[tshemsedinov]

Please rename allowReassignment to reassign

[zoff4ick]

Please rename allowReassignment to reassign

done