SSL legacy support.

Up to now I supported older browsers by supporting older versions of TLS
and cipher suites. I still think it makes sense for my blog, etc. but
not for Nextcloud or GitLab. So here's the first step, make the previous
default SSL configuration be ssl-legacy (split out the common parts to
ssl-common) and next is ssl-modern.

conf.d/default.conf

@@ -8,6 +8,6 @@ server {
 server {
     listen      443 ssl http2 default_server;
     listen      [::]:443 ssl http2 default_server;
-    include     snippets/ssl.conf;
+    include     snippets/ssl-legacy.conf;
     location    / { return 301 https://www.shore.co.il$request_uri; }
 }

snippets/ssl.conf → snippets/ssl-common.conf

@@ -4,8 +4,6 @@ include                     snippets/common-headers.conf;
 ssl_certificate             /var/ssl/site.crt;
 ssl_certificate_key         /var/ssl/site.key;
 ssl_dhparam                 /var/ssl/dhparams;
-ssl_protocols               TLSv1 TLSv1.1 TLSv1.2 TLSv1.3;
-ssl_ciphers                 !AESCCM:!kRSA:!3DES:!RC4:!DES:!MD5:!aNULL:!NULL:AESGCM+ECDH:ECDH+CHACHA20:AES256+ECDH:AES128:CHACHA20:+SHA1;
 ssl_prefer_server_ciphers   on;
 ssl_session_cache           shared:SSL:50m;
 ssl_session_timeout         5m;

snippets/ssl-legacy.conf

+include                     snippets/ssl-common.conf;
+ssl_protocols               TLSv1 TLSv1.1 TLSv1.2 TLSv1.3;
+ssl_ciphers                 !AESCCM:!kRSA:!3DES:!RC4:!DES:!MD5:!aNULL:!NULL:AESGCM+ECDH:ECDH+CHACHA20:AES256+ECDH:AES128:CHACHA20:+SHA1;