feat: simplify non-shadow <slot> logic pt1

[johnjenkins]

What is the current behavior?

GitHub Issue Number: N/A

What is the new behavior?

Swaps out #textNode markers in lightDOM components with actual <slot> nodes, enabling a number of runtime and Dev-QoL improvements:

• all patched / polyfilled methods shrink as finding slot children is much easier: textNode ~ sibling nodes + checks becomes querySelector*
• the viewable source === the actual source of truth
• showing / hiding fallback nodes becomes trivial, changes from: render? Loop through all slotted nodes and do checks to slot:not(:empty) + slot-fb { display: none; }
• builds which include SSR + lightDOM components shrink by up to 4kb

Documentation

Does this introduce a breaking change?

• Yes
• No

Any test snapshots will now have <slot> nodes rendered

Testing

Other information