Some work on the helper to manage IDisposable lifetime with Unity game objects.

[nadako]

To simplify MVVM in Unity we need a set of helpers to bind observable binding lifetimes to unity gameobjects. This PR implements some :)

[codecov-commenter]

Codecov Report

Base: 99.12% // Head: 99.12% // No change to project coverage :thumbsup:

Coverage data is based on head (268e494) compared to base (89ed9d5). Patch has no changes to coverable lines.

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Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #11 +/- ## ======================================= Coverage 99.12% 99.12% ======================================= Files 19 19 Lines 917 917 ======================================= Hits 909 909 Misses 8 8 ``` Help us with your feedback. Take ten seconds to tell us [how you rate us](https://about.codecov.io/nps?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Dan+Korostelev). Have a feature suggestion? [Share it here.](https://app.codecov.io/gh/feedback/?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Dan+Korostelev)

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