build/sqlc: implement simple sqlc/bindata rules

This is a first pass at implementing rules to generate sqlc stubs from
.sql files and embed relevant migration files into bindata.

This is not yet used. The Go API is subject to change - especially the
way migrations are laid out in the generated package will probably
change.

Change-Id: I0873031603957a176ad4664c3b10768b791e0dd5
Reviewed-on: https://review.monogon.dev/c/monogon/+/884
Tested-by: Jenkins CI
Reviewed-by: Leopold Schabel <leo@monogon.tech>
diff --git a/go.sum b/go.sum
index 63a103f..9263021 100644
--- a/go.sum
+++ b/go.sum
@@ -1288,6 +1288,8 @@
 github.com/karrick/godirwalk v1.10.3/go.mod h1:RoGL9dQei4vP9ilrpETWE8CLOZ1kiN0LhBygSwrAsHA=
 github.com/karrick/godirwalk v1.16.1 h1:DynhcF+bztK8gooS0+NDJFrdNZjJ3gzVzC545UNA9iw=
 github.com/karrick/godirwalk v1.16.1/go.mod h1:j4mkqPuvaLI8mp1DroR3P6ad7cyYd4c1qeJ3RV7ULlk=
+github.com/kevinburke/go-bindata v3.23.0+incompatible h1:rqNOXZlqrYhMVVAsQx8wuc+LaA73YcfbQ407wAykyS8=
+github.com/kevinburke/go-bindata v3.23.0+incompatible/go.mod h1:/pEEZ72flUW2p0yi30bslSp9YqD9pysLxunQDdb2CPM=
 github.com/kevinburke/ssh_config v0.0.0-20190725054713-01f96b0aa0cd/go.mod h1:CT57kijsi8u/K/BOFA39wgDQJ9CxiF4nAY/ojJ6r6mM=
 github.com/kisielk/errcheck v1.1.0/go.mod h1:EZBBE59ingxPouuu3KfxchcWSUPOHkagtvWXihfKN4Q=
 github.com/kisielk/errcheck v1.2.0/go.mod h1:/BMXB+zMLi60iA8Vv6Ksmxu/1UDYcXs4uQLJ+jE2L00=