Remove observeEvent anti-pattern from docs

[alexverse]

Updates documentation to avoid observeEvent anti-pattern, and simplifies reactive graphs.

Changes

• How-to Vignette: Communication between modules
• How-to Vignette: Use global variables

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (7d3662f) 17.73% compared to head (b6432d7) 17.73%.

❗ Current head b6432d7 differs from pull request most recent head 86aa6a8. Consider uploading reports for the commit 86aa6a8 to get more accurate results

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Additional details and impacted files

@@           Coverage Diff           @@
##             main     #554   +/-   ##
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  Coverage   17.73%   17.73%           
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  Files           9        9           
  Lines         406      406           
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  Hits           72       72           
  Misses        334      334           

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[kamilzyla]

Thanks @alexverse for spotting this and submitting a fix! 🙏

While reviewing your PR I noticed some pre-existing issues in the examples, e.g.:

1. table_module = app/view/table_module.R in box::use(), where table_module = is unnecessary and .R is forbidden.
2. A reactive that contains that the data (delete that).
3. The utils.R module is not defined. It would be nice to have a simple mock module defined, so that one could copy-paste the examples into a Rhino app and run it.

Perhaps you're up for addressing these as well (in this or a different PR)?

[alexverse]

Thank you @kamilzyla. I will address the other issues you mentioned in a subsequent PR.