fix: allow disabling smart retries [gh-943]

[clample]

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Affected Components

• CLI
• Create CLI
• Test
• Docs
• Examples
• Other

Notes for the Reviewer

Resolves #943

Currently it's not straightforward to disable smart retries. Setting retryStrategy: null for a check gives a type error when using TypeScript (type 'null' is not assignable to type 'RetryStrategy | undefined'). When using JS, the backend Joi default of doubleCheck: true shows in the UI as a linear retry strategy. Currently to disable all retries you need to set both retryStrategy: null and doubleCheck: false.

This PR makes it simpler to disable smart retries. To disable smart retries, the user can just set retryStrategy: null on a check or a group - there's no need to also set doubleCheck: false. When a user sets retryStrategy: null and doesn't set doubleCheck, the CLI will set doubleCheck: false to avoid the Joi default.

This approach of fixing the issue on the CLI side should minimize the breaking changes for users. The only breaking change is that any users that had retryStrategy: null and that weren't setting explicitly setting doubleCheck will have their retries disabled when upgrading to the new CLI version (since the doubleCheck: true default is removed). This shouldn't really have an impact, though.

The PR also adds a RetryStrategyBuilder.noRetries() method to make it more clear/explicit how to disable retries.

[clample]

I couldn't think of a good name that matches the <something>Strategy pattern that we have.

[github-actions]

🎉 Experimental release successfully published on npm

npm install checkly@0.0.0-pr.944.34dcc6c

[umutuzgur]

LGTM