Avoid garbage collection for instrument coordinator components

Explanation of changes

• Keeps track of all instances of InstrumentCoordinatorComponentBase in a class dictionary.
• Changes test such that the integration with QCoDeS is fully tested including garbage collection (main issue of #151 (closed)).

This is a proposal to address #151 (closed). After giving more thought to this I do not see any issue with this implementation. But I might be wrong.

@AdriaanRol is there any use-case that this would violate? I think reloading at least should be safe.

@dcrielaard

Motivation of changes

Closes #151 (closed)

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Merge checklist

See also merge request guidelines

• Merge request has been reviewed and approved by a project maintainer.
• Merge request contains a clear description of the proposed changes and the issue it addresses.
• Merge request made onto appropriate branch (develop for most MRs).
• New code is fully tested.
• New code is documented and docstrings use numpydoc format.
• Changelog has been updated (when applicable).
• CI pipelines pass
  • black code-formatting passes (gitlab-ci),
  • test suite passes (gitlab-ci),
  • no degradation in code-coverage (codacy),
  • no (serious) new pylint code quality issues introduced (codacy),
  • documentation builds successfully (CI and readthedocs),
  • windows tests pass (manually triggered by maintainers before merging).

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