UniStore: Use epoch with microsecond resolution as RV (#92638)

* Use epoch with microsecond resolution as RV

* fix backend tests

* Add solution for when the clock goes back

* Add solution for when the clock goes back

* generate mocks

* go lint

* remove comment

* Use Greatest instead of max in msyql and postgres

* update tests

* Update pkg/storage/unified/sql/sqltemplate/dialect_sqlite.go

Co-authored-by: Diego Augusto Molina <diegoaugustomolina@gmail.com>

* cast to bigint

* add additional round trip

* increment the RV using 2 sql round trips instead of 3

* cleanup comments

* cast unix timestamp to integer

* fix postgres query

* remove old increment test data

* remove greatest

* cast unix_timestamp to signed

* Use statement_timestamp instead of clock_timestamp

---------

Co-authored-by: Diego Augusto Molina <diegoaugustomolina@gmail.com>

pkg/storage/unified/sql/data/resource_version_get.sql

@@ -1,5 +1,6 @@
 SELECT
-        {{ .Ident "resource_version" | .Into .ResourceVersion }}
+        {{ .Ident "resource_version" | .Into .Response.ResourceVersion }},
+        {{ .CurrentEpoch | .Into .Response.CurrentEpoch }}
     FROM {{ .Ident "resource_version" }}
     WHERE 1 = 1
         AND {{ .Ident "group" }}    = {{ .Arg .Group }}

pkg/storage/unified/sql/data/resource_version_insert.sql

@@ -8,6 +8,6 @@ INSERT INTO {{ .Ident "resource_version" }}
     VALUES (
         {{ .Arg .Group }},
         {{ .Arg .Resource }},
-        2
+        {{ .CurrentEpoch }}
     )
 ;

pkg/storage/unified/sql/data/resource_version_update.sql

@@ -1,6 +1,6 @@
 UPDATE {{ .Ident "resource_version" }}
 SET
-    {{ .Ident "resource_version" }} = {{ .Arg .ResourceVersion}}
+    {{ .Ident "resource_version" }} = {{ .Arg .ResourceVersion }}
 WHERE 1 = 1
     AND {{ .Ident "group" }}    = {{ .Arg .Group }}
     AND {{ .Ident "resource" }} = {{ .Arg .Resource }}