component/firefox: add version 78.1.0esr

This is based on commit "Firefox Version Up to 78.1.0esr", but it does not
replace the default firefox, just enable a new version for now.

component/firefox/buildout.cfg

@@ -51,6 +51,11 @@ install =
   ))
     os.fchmod(f.fileno(), 0o755)
 
+[firefox-wrapper-78]
+<= firefox-wrapper
+wrapper-name = firefox-78
+part = ${firefox-78:location}
+
 [firefox-wrapper-68]
 <= firefox-wrapper
 wrapper-name = firefox-68
@@ -95,6 +100,12 @@ cache-dir =
 # would not be created.
 <= firefox-68
 
+[firefox-78]
+<= firefox-download
+version = 78.1.0esr
+i686-md5sum = 09595a1b9a99d17a618a51bc1f971e5e
+x86_64-md5sum = 06f4d488721ce7229d9a86cb4c6786f3
+
 [firefox-68]
 <= firefox-download
 version = 68.0.2esr