Correlations: Add GetCorrelation(s) HTTP APIs (#52517)

* Correlations: Get Single correlations

* Correlations: Get all correlations for given source ds

* Correlations: Get all correlations

* add tests

* add DB indices

* fix lint errors

* remove skip from tests

* use DatasourceService in test

pkg/tests/api/correlations/common_test.go

@@ -43,6 +43,20 @@ type User struct {
 	password string
 }
 
+type GetParams struct {
+	url  string
+	user User
+}
+
+func (c TestContext) Get(params GetParams) *http.Response {
+	c.t.Helper()
+
+	resp, err := http.Get(c.getURL(params.url, params.user))
+	require.NoError(c.t, err)
+
+	return resp
+}
+
 type PostParams struct {
 	url  string
 	body string
@@ -127,7 +141,7 @@ func (c TestContext) createUser(cmd user.CreateUserCommand) {
 func (c TestContext) createDs(cmd *datasources.AddDataSourceCommand) {
 	c.t.Helper()
 
-	err := c.env.SQLStore.AddDataSource(context.Background(), cmd)
+	err := c.env.Server.HTTPServer.DataSourcesService.AddDataSource(context.Background(), cmd)
 	require.NoError(c.t, err)
 }