Create end-to-end testing framework and CI workflows

[mjcheetham]

There have been several bugs over the lifetime of GCM that have occurred around installation or platform integration that were not caught in unit or manual testing. To avoid such issues going forward we propose creating a CI workflow, for all supported platforms, that runs a basic suite of integration or end-to-end tests including installation, basic authentication flows, and uninstallation.

We should be able to achieve this using GitHub hosted runners and a matrix workflow that runs the appropriate installer and performs simple authentication actions.

There are two options (not mutually exclusive) for handling UI prompts:

1. Replace the UI components with a 'test' UI helper that is drivable by the test harness.
2. Use a tool like AutoHotkey (Windows only) on platforms that have a free and easy to use UI automation tool.

[ldennington]

As mentioned by @derrickstolee in #1045 we should make sure we include an end-to-end test to validate TRACE2 event/normal output as part of this effort.

[ldennington]

Potential scenarios to cover:

scenario	test type	provider(s)	platform(s)	credstore(s)	framework
get with existing credential	integration	Bitbucket, GitHub, GitLab, Generic	macOS, Linux, Windows, WSL	Keychain, Credential Manager, Secret Service, GPG/Pass	Cucumber
get without existing credential	integration	Bitbucket, GitHub, GitLab, Generic	macOS, Linux, Windows, WSL	Keychain, Credential Manager, Secret Service, GPG/Pass	Cucumber
store	integration	Bitbucket, GitHub, GitLab, Generic	macOS, Linux, Windows, WSL	Keychain, Credential Manager, Secret Service, GPG/Pass	Cucumber
erase	integration	Bitbucket, GitHub, GitLab, Generic	macOS, Linux, Windows, WSL	Keychain, Credential Manager, Secret Service, GPG/Pass	Cucumber
TRACE/TRACE2 output validation	integration	N/A	macOS, Linux, Windows, WSL	N/A	Cucumber
OAuth using GUI	end-to-end	Bitbucket, GitHub, GitLab	macOS, Linux, Windows, WSL	Keychain, Credential Manager, Secret Service, GPG/Pass	TBD
OAuth using Terminal	end-to-end	Bitbucket, GitHub, GitLab	macOS, Linux, Windows, WSL	Keychain, Credential Manager, Secret Service, GPG/Pass	Cucumber
Device code using GUI	end-to-end	Bitbucket, GitHub, GitLab	macOS, Linux, Windows, WSL	Keychain, Credential Manager, Secret Service, GPG/Pass	TBD
Device code using Terminal	end-to-end	Bitbucket, GitHub, GitLab	macOS, Linux, Windows, WSL	Keychain, Credential Manager, Secret Service, GPG/Pass	Cucumber
PAT using GUI	end-to-end	Bitbucket, GitHub, GitLab	macOS, Linux, Windows, WSL	Keychain, Credential Manager, Secret Service, GPG/Pass	TBD
PAT using Terminal	end-to-end	Bitbucket, GitHub, GitLab	macOS, Linux, Windows, WSL	Keychain, Credential Manager, Secret Service, GPG/Pass	Cucumber
Username/password using GUI	end-to-end	Bitbucket, GitLab, Generic	macOS, Linux, Windows, WSL	Keychain, Credential Manager, Secret Service, GPG/Pass	TBD
Username/password using Terminal	end-to-end	Bitbucket, GitLab, Generic	macOS, Linux, Windows, WSL	Keychain, Credential Manager, Secret Service, GPG/Pass	Cucumber

Candidates for UI testing:

• Appium
• Avalonia + Custom XUnit Framework