Switch images to svgs, where possible (#1563)

Closes #1361, #1362

_includes/sections/search-engines.html

@@ -6,7 +6,7 @@
 
 {% include cardv2.html
 title="searx - Decentral"
-image="/assets/img/provider/searx.png"
+image="/assets/img/svg/3rd-party/searx.svg"
 description='searx is an <a href="https://github.com/asciimoo/searx">open-source</a> metasearch engine, aggregating the results of other search engines while not storing information about its users. No logs, no ads and no tracking. There is a <a href="https://github.com/asciimoo/searx/wiki/Searx-instances">list of public instances</a>, or you can try <a href="https://search.privacytools.io/">the PrivacyTools Search</a>'
 website="https://searx.me/"
 tor="http://ulrn6sryqaifefld.onion"
@@ -16,7 +16,7 @@ github="https://github.com/asciimoo/searx"
 
 {% include cardv2.html
 title="DuckDuckGo - USA"
-image="/assets/img/provider/DuckDuckGo.png"
+image="/assets/img/svg/3rd-party/duckduckgo.svg"
 description='DuckDuckGo is a "search engine that doesn\'t track you." Some of DuckDuckGo\'s code is free software hosted at GitHub, but the core is proprietary. <span class="flag-icon flag-icon-us"></span> <a href="../../providers/#ukusa">The company is based in the USA.</a>'
 website="https://duckduckgo.com/"
 tor="http://3g2upl4pq6kufc4m.onion"
@@ -26,7 +26,7 @@ github="https://github.com/duckduckgo"
 
 {% include cardv2.html
 title="Qwant - France"
-image="/assets/img/provider/Qwant.png"
+image="/assets/img/svg/3rd-party/qwant.svg"
 description='Qwant is a search engine with its philosophy based on two principles: no user tracking and no filter bubble. Qwant was launched in France in February 2013.'
 website="https://www.qwant.com/"
 forum="https://forum.privacytools.io/t/discussion-qwant/286"