Allow providing custom selector instead of label for actions

[mondaychen]

No description provided.

[lynchee-owo]

TODO:

• export 4 types: the main action type and three sub action types (selector, label, and elementId)
• export a generic performAction that calls three sub performActions{selector/label/elementId} based on action type.
• refactor available actions

Test and Release:

• change npm package version (beta) in package.lib.json
• run the build lib script to generate dist-lib
• run npm publish --tag beta2 in dist-lib
• now the new version is published. use that in wingmate to test
• if things are working properly, publish the official version (remove beta tag)

[lynchee-owo]

bugs found when completing this task:

1. the fallback selector (visible-text) cannot be properly applied such that the corresponding element cannot be found.