Update karax.nim

[scattergory]

use tests for mathML and SVG nodes to make these elements write to the DOM correctly by default

[geotre]

Hi @scattergory thanks for the PR. There have been a few attempts previously at adding SVG/namespace support, so I would like to check back on those to understand the changes they were looking to add.

It would also be good to add tests to ensure that it works correctly.

Please ping me when it is ready to check (if you can unify #255 in as well please) and I will look over this as soon as possible

[choltreppe]

Hey, I'd like to push this PR over the finish line, how can I do that ?

[Araq]

Error: execution of an external program failed: '/__w/karax/karax/tests/tester '
.......................................
/__w/karax/karax/karax/kdom.nim(9, 10) Hint: duplicate import of 'dom'; previous import here: /__w/karax/karax/karax/kdom.nim(3, 6) [DuplicateModuleImport]
/__w/karax/karax/karax/kdom.nim(3, 6) Warning: imported and not used: 'dom' [UnusedImport]
.......................
/__w/karax/karax/karax/vstyles.nim(329, 22) Warning: implicit conversion to 'cstring' from a non-const location: aj[0]; this will become a compile time error in the future [CStringConv]
/__w/karax/karax/karax/vstyles.nim(329, 29) Warning: implicit conversion to 'cstring' from a non-const location: aj[1]; this will become a compile time error in the future [CStringConv]
.
/__w/karax/karax/karax/vdom.nim(72, 3) Hint: 'svgElements' is declared but not used [XDeclaredButNotUsed]
/__w/karax/karax/karax/vdom.nim(74, 3) Hint: 'mathElements' is declared but not used [XDeclaredButNotUsed]
.....
/__w/karax/karax/karax/karax.nim(199, 8) Error: undeclared identifier: 'svgElements'

Remember that parts of the Karax DOM also work with the native backends.

[geotre]

I think we can close this PR as it has been superseded by #261