Signed-off-by: Markus Heiser <markus.heiser@darmarit.de>

This PR adds a new result type: File

    Python class: searx/result_types/file.py
    Jinja template: searx/templates/simple/result_templates/file.html
    CSS (less) client/simple/src/less/result_types/file.less

Class 'File' (singular) replaces template 'files.html' (plural).  The renaming
was carried out because there is only one file (singular) in a result. Not to be
confused with the category 'files' where in multiple results can exist.

As mentioned in issue [1], the class '.category-files' was removed from the CSS
and the stylesheet was adopted in result_types/file.less (there based on the
templates and no longer based on the category).

[1] https://github.com/searxng/searxng/issues/5198

Signed-off-by: Markus Heiser <markus.heiser@darmarit.de>

Everyone should have already switched from legacy methods

A macro named 'result_footer_rtl' does not exists.

Signed-off-by: Markus Heiser <markus.heiser@darmarit.de>

With LESS function '.show-content-button' all the *Show-Media* links becomes
bottons.

Signed-off-by: Markus Heiser <markus.heiser@darmarit.de>

Rename result field data_src to iframe_src

Suggested-by: @dalf https://github.com/searxng/searxng/pull/882#issuecomment-1037997402
Signed-off-by: Markus Heiser <markus.heiser@darmarit.de>

Embedded HTML breaks SearXNG architecture.  To modularize, HTML is generated in
the templates (oscar & simple) and result parameter 'embedded' is replaced by
'data_src' (and 'audio_src'), an URL for embedded content (<iframe>).

Signed-off-by: Markus Heiser <markus.heiser@darmarit.de>

Signed-off-by: Markus Heiser <markus.heiser@darmarit.de>