Allow common redis and leveldb connections (#12385)

* Allow common redis and leveldb connections

Prevents multiple reopening of redis and leveldb connections to the same
place by sharing connections.

Further allows for more configurable redis connection type using the
redisURI and a leveldbURI scheme.

Signed-off-by: Andrew Thornton <art27@cantab.net>

* add unit-test

Signed-off-by: Andrew Thornton <art27@cantab.net>

* as per @lunny

Signed-off-by: Andrew Thornton <art27@cantab.net>

* add test

Signed-off-by: Andrew Thornton <art27@cantab.net>

* Update modules/cache/cache_redis.go

* Update modules/queue/queue_disk.go

* Update modules/cache/cache_redis.go

* Update modules/cache/cache_redis.go

* Update modules/queue/unique_queue_disk.go

* Update modules/queue/queue_disk.go

* Update modules/queue/unique_queue_disk.go

* Update modules/session/redis.go

Co-authored-by: techknowlogick <techknowlogick@gitea.io>
Co-authored-by: Lauris BH <lauris@nix.lv>

go.mod

@@ -38,7 +38,7 @@ require (
 	github.com/go-enry/go-enry/v2 v2.5.2
 	github.com/go-git/go-billy/v5 v5.0.0
 	github.com/go-git/go-git/v5 v5.1.0
-	github.com/go-redis/redis v6.15.2+incompatible
+	github.com/go-redis/redis/v7 v7.4.0
 	github.com/go-sql-driver/mysql v1.5.0
 	github.com/go-swagger/go-swagger v0.25.0
 	github.com/go-testfixtures/testfixtures/v3 v3.4.0
@@ -88,6 +88,7 @@ require (
 	github.com/shurcooL/httpfs v0.0.0-20190527155220-6a4d4a70508b // indirect
 	github.com/shurcooL/vfsgen v0.0.0-20181202132449-6a9ea43bcacd
 	github.com/stretchr/testify v1.6.1
+	github.com/syndtr/goleveldb v1.0.0
 	github.com/tecbot/gorocksdb v0.0.0-20181010114359-8752a9433481 // indirect
 	github.com/tinylib/msgp v1.1.2 // indirect
 	github.com/tstranex/u2f v1.0.0