fix: NativescriptQueryRunner's query method fails when targeting es2017

[pekevski]

Making the promise async now correctly scopes the handler. this.driver is now defined.
Additional corrections were made to the syntax, eg conditionals.

Closes #8180

Description of change

I believe making the promise async will now correctly scope this in the handler function. When it references this.driver, on running a query the app would throw an exception stating that driver was undefined.

Tested this change with NS8 projects and it doesn't throw the error anymore.

Pull-Request Checklist

• Code is up-to-date with the master branch
• npm run lint passes with this change
• npm run test passes with this change
• This pull request links relevant issues as Fixes #0000
• There are new or updated unit tests validating the change N/A
• Documentation has been updated to reflect this change N/A
• The new commits follow conventions explained in CONTRIBUTING.md

[imnotjames]

I'm going to change the title of this PR to

fix: NativescriptQueryRunner's query method fails when targeting es2017 - what do you think? That'll be the message that shows up on the commit, as well.

[pekevski]

Yep 👍 sounds good to me. Thank you