feat: search all fields (#622)

* ✨ feat(search): search all feature

- add Description field to Gist struct and index it
- extend SearchGistMetadata with Description and Content
- update Bleve and Meilisearch to index and search Description
- modify ParseSearchQueryStr to parse description: and content: keywords
- update templates and i18n for new search options

* Fix test

* Set content by default

Signed-off-by: Thomas Miceli <tho.miceli@gmail.com>

* Config to define default searchable fields

Signed-off-by: Thomas Miceli <tho.miceli@gmail.com>

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Signed-off-by: Thomas Miceli <tho.miceli@gmail.com>
Co-authored-by: Thomas Miceli <tho.miceli@gmail.com>

internal/i18n/locales/en-US.yml

@@ -88,10 +88,12 @@ gist.search.found: gists found
 gist.search.no-results: No gists found
 gist.search.help.user: gists created by user
 gist.search.help.title: gists with given title
+gist.search.help.description: gists with given description
 gist.search.help.filename: gists having files with given name
 gist.search.help.extension: gists having files with given extension
 gist.search.help.language: gists having files with given language
 gist.search.help.topic: gists with given topic
+gist.search.help.all: search all fields
 gist.search.placeholder.title: Title
 gist.search.placeholder.visibility: Visibility
 gist.search.placeholder.public: Public