Improve type safety of DOM elements on core/dom

[mattpap]

Previously constructs like div({style: {margin: "10px"}, tabIndex: 0}, ...) were pretty much dynamically typed. This PR fixes that problem and fixes any discovered issues.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 92.59%. Comparing base (e61219b) to head (721670e).
Report is 37 commits behind head on branch-3.5.

❗ Current head 721670e differs from pull request most recent head 00dda62. Consider uploading reports for the commit 00dda62 to get more accurate results

Additional details and impacted files

@@              Coverage Diff               @@
##           branch-3.5   #13735      +/-   ##
==============================================
+ Coverage       91.57%   92.59%   +1.01%     
==============================================
  Files             326      325       -1     
  Lines           20737    20729       -8     
==============================================
+ Hits            18990    19194     +204     
+ Misses           1747     1535     -212     

[mattpap]

I tried to use some advanced types to extract relevant attributes from TS' dom.d.ts standard library, but that doesn't work reliably and increases type-checking times, so I opted for a curated list of supported attributes for each element that we use. Much simpler and robust, and if an attribute is missing then one can set if after construction. Anyway, this is an API for internal usage, so we can always update the list if needed.