Make GenericNode generic over the event type

[lukechu10]

This allows creating rendering backends that do not use web_sys::Event in event handlers

[codecov-commenter]

Codecov Report

Merging #297 (7436d0c) into master (d17e776) will not change coverage.
The diff coverage is 33.33%.

@@           Coverage Diff           @@
##           master     #297   +/-   ##
=======================================
  Coverage   74.93%   74.93%           
=======================================
  Files          33       33           
  Lines        4800     4800           
=======================================
  Hits         3597     3597           
  Misses       1203     1203           

Impacted Files	Coverage Δ
packages/sycamore-router/src/router.rs	25.76% <0.00%> (ø)
packages/sycamore/src/generic_node/dom_node.rs	0.00% <0.00%> (ø)
packages/sycamore/src/generic_node/ssr_node.rs	76.45% <100.00%> (ø)

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update d17e776...7436d0c. Read the comment docs.