feat(sterni/machines): add edwin

This adds edwin, the machine running sterni.lv, as well as my
idiosyncratic deployment solution. It is based on instantiating the
system configuration locally (where you'd work on the configuration),
copying the derivation files to the remote machine where the system
derivation is realised and deployed. Unfortunately, the first step tends
to be quite slow (despite gzip compression), so this may not be the
definite way despite its advantages.

Change-Id: I30f597692338df3981e01a1b7eee9cdad48f94cb
Reviewed-on: https://cl.tvl.fyi/c/depot/+/7293
Reviewed-by: sterni <sternenseemann@systemli.org>
Tested-by: BuildkiteCI

users/sterni/secrets/warteraum-tokens.age

@@ -0,0 +1,10 @@
+age-encryption.org/v1
+-> ssh-ed25519 aXKGcg yHE1bla5BN1Kgows1tdeswamJQHfzGpv8fL3qZs04k0
+rR1O25EIQXctnyVsQCZO47bM44KFhmOZ7ePiecKrZ40
+-> ssh-ed25519 34g70A voVJDU9DIrT0z6X/mAi0tQqXthRZAyrzsPXOTIIzKUw
+yEiIaD9jblO44/RaoiPA0mjvRToNc4Ur9GcwfG9TSVo
+-> =UOH^-Z4-grease Do<;So
+l0F72v4UD8r5kbpNIT2i1IUT6ttXZhuPE91H2tucMc5TKRvGDvpdJNpQ+P+XmX2M
+661iYooyust5TGZsXJFHVYg
+--- To85A7ohH2Sjfy8js2+JzV0c86dmDO2JCH8TK7OtVtM
+Œ¾VÃq·%n!óM#`3­°Ç;1
îúßwFª¦Cç<43>ªH'îèYÄò‚å­˜]Ì-„þè½Q1Äž •«Ëm