Stability fixes

[helto4real]

Breaking change

Proposed change

Some quality and stability fixes.

• [x] Make the dispose of application context thread safe
• [x] Correct sample of use calendar in debug project
• [x] Make the handling of usage of cancellation token that could potentially be used from a disposed or canceled Cancellation token source, check screenshot

Type of change

• [ ] Dependency upgrade
• [x] Bugfix (non-breaking change which fixes an issue)
• [ ] New feature (which adds functionality to an existing integration)
• [ ] Breaking change (fix/feature causing existing functionality to break)
• [x] Code quality improvements to existing code or addition of tests

Additional information

• This PR fixes or closes issue: fixes #
• This PR is related to issue:
• Link to documentation pull request:

Checklist

• [x] The code change is tested and works locally.
• [x] Local tests pass. Your PR cannot be merged unless tests pass
• [x] The code compiles without warnings (code quality check)
• [ ] Tests have been added to verify that the new code works.

If user exposed functionality or configuration are added/changed:

• [ ] Documentation added/updated for http://netdaemon.xtz