Add `isPresent` command.

[dikwickley]

Thanks in advance for your contribution. Please follow the below steps in submitting a pull request, as it will help us with reviewing it quicker.

The isPresent command was quite tricky as there were few edge cases we had to solve. The main one being when the element in not present, we don't want to show the Timeout Error if there is a isPresent command chained (which should ideally return false).

I solved this by checking if the next sibling of a find command is an elementIsPresent command. It still takes 5 seconds to try to resolve the element.

If this approach looks good, I can add some tests for this too.

Sanity for elements that are not present:

• [x] Before marking your PR for review, please test and verify your changes by making appropriate modifications to any of the Nightwatch example tests (present in examples/tests directory of the project) and running them. ecosia.js and duckDuckGo.js are good examples to work with.
• [x] Create a new branch from master (e.g. features/my-new-feature or issue/123-my-bugfix);
• [x] If you're fixing a bug also create an issue if one doesn't exist yet;
• [ ] If it's a new feature explain why do you think it's necessary. Please check with the maintainers beforehand to make sure it is something that we will accept. Usually we only accept new features if we feel that they will benefit the entire community;
• [x] Please avoid sending PRs which contain drastic or low level changes. If you are certain that the changes are needed, please discuss them beforehand and indicate what the impact will be;
• [x] If your change is based on existing functionality please consider refactoring first. Pull requests that duplicate code will most likely be ignored;
• [x] Do not include changes that are not related to the issue at hand;
• [x] Follow the same coding style with regards to spaces, semicolons, variable naming etc.;
• [ ] Always add unit tests - PRs without tests are most of the times ignored.

[github-actions[bot]]

Status

• ❌ No modified files found in the types directory. Please make sure to include types for any changes you have made. Thank you!.

[pujagani]

There are some failing tests. Not sure if it is due to the changes made here. Can you help take a look? Thank you!

[dikwickley]

@pujagani yes, fixed those. There was a missing check for outofbounds index.

[AutomatedTester]

I think the test that is failing is flakey.

I can't see a test for this change can we add one?

[dikwickley]

@garg3133 @AutomatedTester ready for review!