feat: Add `initialCursor` to code editor when setting the active file

[mattphillips]

What kind of change does this pull request introduce?

This PR closes https://github.com/codesandbox/sandpack/issues/558

What is the current behavior?

Currently sandpack has a setActiveFile function that can only open the file without putting the cursor at a given position.

What is the new behavior?

This PR adds an optional cursor (line / column numbers) to the setActiveFile function. If a cursor position is set as part of this function then the CodeMirror state has a selection at the given cursor and will scroll it into view and focus the editor.

This PR also introduces a change to SandpackTests. I've rewritten the FormattedErrors component to use JSX instead of relying of string manipulation and dangerously rendering the string. The reason to do this is so that we can safely attach an onClick to the failing matcher error which will open the test file at the correct position to fix the matcher.

What steps did you take to test this? This is required before we can merge, make sure to test the flow you've updated.

See attached demo of the cursor change in action using SandpackTests errors.

https://user-images.githubusercontent.com/5610087/188724977-099ca5d5-b5cc-43a0-b45d-9cd9420a6968.mov

Checklist

• [ ] Documentation;
• [x] Storybook (if applicable);
• [ ] Tests;
• [ ] Ready to be merged;

Todo

• I'm going to hold off updating the docs until @danilowoz has had a chance to look this over and he's happy with everything I'll get the docs updated too.

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[mattphillips]

Hey @danilowoz 👋 have you had a chance to look at this? Anything you need me to change or do?

[danilowoz]

Hey, I'm going to close this, as it has been a while. Feel free to reopen it anytime Thanks!