bugfix(button): only install isr service once

[finger563]

Description

• Update button constructor to have a static bool tracking if the isr service was installed and if so, do not install it again
• Updated example to have another button to ensure multiple buttons are supported with no warnings or anything

Motivation and Context

If you have multiple buttons, you get the following error:

Note: This is a benign error as both buttons still work, but I don't like errors hence this PR :)

How has this been tested?

Building and running the example.

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.