Fix detection of old Bokeh in notebook load script

[philippjfr]

The notebook load script was designed to detect old versions of Bokeh (and Panel) and potentially run multiple copies of the libraries side-by-side. It did this by comparing the global Bokeh object version, if already defined, to the new version being loaded. However it seems like scoping rules meant that in some cases it was comparing a local Bokeh variable rather than the global window.Bokeh object, which meant that it would incorrectly detect that Bokeh should be replaced, but then later correctly detect that it doesn't actually have to reload Bokeh. This meant that it would unload Bokeh and then not reload it.

Additionally I've found that due to escaping rules meant that special characters (such as ^) in URLs would be escaped so that some of the checks that tried to ensure libraries weren't loaded twice were not detecting this correctly because they compared escaped with non-escaped URIs. We now escape them using the escapeURI function before comparing.

Fixes #7264

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 82.18%. Comparing base (b00840c) to head (d0ffffd).
Report is 3 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #7269   +/-   ##
=======================================
  Coverage   82.18%   82.18%           
=======================================
  Files         337      337           
  Lines       50359    50359           
=======================================
+ Hits        41387    41389    +2     
+ Misses       8972     8970    -2     

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[hoxbro]

I'm very happy with this PR.