feat(adc): Add mutex ensuring OneshotAdc can be used safely from multiple threads

[finger563]

Description

• Add mutex to OneshotAdc APIs
• Remove warning in continuous ADC

Motivation and Context

Ensures that the oneshot adc can safely be used from multiple threads

How has this been tested?

Building and running adc/example on a QtPy ESP32s3.

Screenshots (if appropriate, e.g. schematic, board, console logs, lab pictures):

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Documentation Update
• Hardware (schematic, board, system design) change
• Software change

Checklist:

• My change requires a change to the documentation.
• I have added / updated the documentation related to this change via either README or WIKI

Software

• I have added tests to cover my changes.
• I have updated the .github/workflows/build.yml file to add my new test to the automated cloud build github action.
• All new and existing tests passed.
• My code follows the code style of this project.

[github-actions]

✅Static analysis result - no issues found! ✅