chore: add presubmit and continuous kokoro tests (#5229)

* chore: add kokoro configs for running tests on PHP 7.4 and 8.0

* update PHP version for docs

* use php80 for continuous tests

* update kokoro to ues php 8 for docs gen

* update cs library and fix cs

* hopefully fix tests

* Revert "hopefully fix tests"

This reverts commit 60fe1387b5e1d22159f1cee001d4e1078dd3b448.

* fix tests for PHP 7.4

* Update docs.yml

* remove 8.0

tests/Unit/FirestoreSessionHandlerTest.php

@@ -56,7 +56,8 @@ public function setUp()
     public function testOpen()
     {
         $this->connection->beginTransaction(['database' => $this->dbName()])
-            ->shouldBeCalledTimes(1);
+            ->shouldBeCalledTimes(1)
+            ->willReturn(['transaction' => null]);
         $firestoreSessionHandler = new FirestoreSessionHandler(
             $this->connection->reveal(),
             $this->valueMapper->reveal(),
@@ -90,6 +91,9 @@ public function testOpenWithException()
      */
     public function testReadNotAllowed()
     {
+        $this->connection->beginTransaction(['database' => $this->dbName()])
+            ->shouldBeCalledTimes(1)
+            ->willReturn(['transaction' => null]);
         $firestoreSessionHandler = new FirestoreSessionHandler(
             $this->connection->reveal(),
             $this->valueMapper->reveal(),
@@ -124,7 +128,8 @@ public function testReadNothing()
             ->shouldBeCalledTimes(1)
             ->willReturn(null);
         $this->connection->beginTransaction(['database' => $this->dbName()])
-            ->shouldBeCalledTimes(1);
+            ->shouldBeCalledTimes(1)
+            ->willReturn(['transaction' => null]);
         $this->connection->batchGetDocuments([
             'database' => $this->dbName(),
             'documents' => [$this->documentName()],
@@ -150,7 +155,8 @@ public function testReadNothing()
     public function testReadWithException()
     {
         $this->connection->beginTransaction(['database' => $this->dbName()])
-            ->shouldBeCalledTimes(1);
+            ->shouldBeCalledTimes(1)
+            ->willReturn(['transaction' => null]);
         $this->connection->batchGetDocuments([
             'database' => $this->dbName(),
             'documents' => [$this->documentName()],
@@ -186,7 +192,8 @@ public function testReadEntity()
             ->shouldBeCalledTimes(1)
             ->willReturn(['data' => 'sessiondata']);
         $this->connection->beginTransaction(['database' => $this->dbName()])
-            ->shouldBeCalledTimes(1);
+            ->shouldBeCalledTimes(1)
+            ->willReturn(['transaction' => null]);
         $this->connection->batchGetDocuments([
             'database' => $this->dbName(),
             'documents' => [$this->documentName()],
@@ -217,7 +224,8 @@ public function testWrite()
                 return ['data' => ['stringValue' => 'sessiondata']];
             });
         $this->connection->beginTransaction(['database' => $this->dbName()])
-            ->shouldBeCalledTimes(1);
+            ->shouldBeCalledTimes(1)
+            ->willReturn(['transaction' => null]);
         $this->connection->commit([
             'database' => $this->dbName(),
             'writes' => [