Make SsrNode automatically create reactive nodes by default

[lukechu10]

Previous behavior: dynamic nodes created on the server were not actually dynamic, i.e. the values would not update even when signals are updated.

New behavior: dynamic nodes are always dynamic. This solves a bunch of inconsistencies and makes it easier to use resources which update the value dynamically.

[codecov]

Codecov Report

Attention: Patch coverage is 65.90909% with 15 lines in your changes missing coverage. Please review.

Project coverage is 72.10%. Comparing base (9f06fd5) to head (9f9869f).
Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
packages/sycamore-web/src/node/ssr_node.rs	60.52%	15 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #737      +/-   ##
==========================================
+ Coverage   71.84%   72.10%   +0.26%     
==========================================
  Files          44       44              
  Lines        6282     6334      +52     
==========================================
+ Hits         4513     4567      +54     
+ Misses       1769     1767       -2     

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