Don't render until initial data loaded

[colin-grant-work]

What it does

Fixes #145 by not showing the main UI until the initial memory data is known.

How to test

1. Open a Memory Inspector view from the Variables view.
2. Observe that there is not a stage where Formik errors are shown indicating that Address and Count are required.

Review checklist

• as an author, I have thoroughly tested my changes and carefully followed the contribution guidelines

Reminder for reviewers

• as a reviewer, I agree to behave in accordance with the code of conduct

[colin-grant-work]

There are two different approaches represented in the different commits:

• The first commit shows a small loading spinner until the first setOptions call is received.
• The second commit reverts that and instead passes the initial options in the HTML itself, allowing it to be retrieved when the view is initialized.

Other approaches are possible, feel free to suggest your favorite.

[jreineckearm]

Thanks for spotting and fixing this, @colin-grant-work !

Had a look at both options:

1. Having a hard time to see the spinner appear in my setup. So, can't really say how it looks like and where it appears. Except from that, if you open an empty Memory Inspector window through the command palette, the Formik error doesn't show anymore.
2. Works nicely, and the error is shown as expected after opening an empty window through the command palette.

Even if the code changes for the first approach seem less intrusive, I believe we should go with the second solution which is already the top commit. Hence approved.