[pkg/ottl] Add IsBool Converter

[els0r]

Description:
Add isBool OTTL function that returns true if the target is a bool and returns false if it is not

Link to tracking Issue: #27897

Testing: Added tests

Documentation: Updated README and added CHANGELOG entry

[linux-foundation-easycla]

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[TylerHelmuth]

@els0r thank you for joining Contribest and for your contribution. Unfortunately we made a mistake with this issue as there is already a prior PR submitted for this Converter: #27900. Since it came first, we'll take the other PR, but thanks for engaging with us anyways!

If the other PRs doesn't get merged for whatever reason I'll reopen this one.