Fix for the cursor height and positioning relative to the text and font

[hanbollar]

Linking

related to #590

Problem

cursor positioning is at top of line with odd bottom offset (due to line height having a bit on top of the text itself so it doesnt exactly match fontsize)

goal:

(this is an inprogress photo - but it shows goal of positioning at proper 'height' in line, though the cursor's own height doesnt yet match the fontsize for the line)

Solution

Quick explanation of change to be done

Breaking Change

If this is a breaking change describe the before and after and why the change was necessary

Notes

• get cursor's height positioning right in the line
• get cursor's physical height to match font size <-- remaining todo

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Required to Merge

• PASS - all necessary actions must pass (excluding the auto-skipped ones)
• TEST IN HEADSET - main dev-testing-example and any of the other examples still work as expected
• VIDEO - if this pr changes something visually - post a video here of it in headset-MR and/or on desktop (depending on what it affects) for the reviewer to reference.

cursor.mov

• TITLE - make sure the pr's title is updated appropriately as it will be used to name the commit on merge
  - [ ] BREAKING CHANGE
  • DOCUMENTATION: This includes any changes to html tags and their components
    • make a pr in the documentation repo that updates the manual docs to match the breaking change
    • link the pr of the documentation repo here: #pr
    • that pr must be approved by @lobau
  • SAMPLES/INDEX.HTML: This includes any changes (html tags or otherwise) that must be done to our landing page submodule as an effect of this pr's updates
    • make a pr in the mrjs landing page repo that updates the landing page to match the breaking change
    • link the pr of the landing page repo here: #pr
    • that pr must be approved by @hanbollar

[render]

Your Render PR Server URL is https://examples-mrjs-pr-588.onrender.com.

Follow its progress at https://dashboard.render.com/static/srv-coep59un7f5s73fa3p30.