Make the search feature configurable and toggleable

[caendesilva]

Make the search feature configurable and toggleable.

Also adds documentation to the dev-docs.

Also automatically generates the search index when running hyde build.

Some code refactoring and cleanup. Bugfixes. UX/UI niceties.

[codecov-commenter]

Codecov Report

Merging #467 (dce89ce) into master (6417707) will not change coverage.
The diff coverage is n/a.

@@            Coverage Diff            @@
##            master      #467   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files            1         1           
  Lines           11        11           
=========================================
  Hits            11        11           

Impacted Files	Coverage Δ
config/hyde.php	100.00% <ø> (ø)

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