feat(removeListeners): allow removing onChange listeners

[jabreuar]

Pull request checklist

Please check if your PR fulfills the following requirements:

• [ ] Docs have been reviewed and added / updated if needed (for bug fixes / features)
• [x] Build (npm run build) was run locally and any changes were pushed
• [x] Tests (npm test) were run locally and passed
• [x] Prettier (npm run prettier) was run locally and passed

Pull request type

Please check the type of change your PR introduces:

• [ ] Bugfix
• [x] Feature
• [ ] Refactoring (no functional changes, no api changes)
• [ ] Build related changes
• [ ] Documentation content changes
• [ ] Other (please describe):

What is the current behavior?

GitHub Issue Number: https://github.com/stenciljs/store/issues/439

What is the new behavior?

• Provide a clear API to remove a change listener.

Does this introduce a breaking change?

• [ ] Yes
• [x] No

Testing

Other information

[christian-bromann]

It seems like there are some issues with Prettier:

> @stencil/[email protected] prettier.base
> prettier --cache 'src/**/*.ts' --list-different

src/observable-map.test.ts
src/observable-map.ts
src/types.ts

Let me know if I can help.

[jabreuar]

It seems like there are some issues with Prettier:

> @stencil/[email protected] prettier.base
> prettier --cache 'src/**/*.ts' --list-different

src/observable-map.test.ts
src/observable-map.ts
src/types.ts

Let me know if I can help.

let me fix them

[christian-bromann]

@jabreuar anything I can do to help?