Properly deprecate db_driver, db_escape_field, db_escape_table, db_rename_table, db_drop_index, db_drop_unique_key, db_add_unique_key, db_drop_primary_key, db_add_primary_key

Using the grep statement in IS, this is the current situation:

./core/includes/database.inc:function db_escape_table($table) {
./core/includes/database.inc:function db_escape_field($field) {
./core/includes/database.inc:function db_driver() {
./core/includes/database.inc:function db_rename_table($table, $new_name) {
./core/includes/database.inc:function db_add_primary_key($table, $fields) {
./core/includes/database.inc:function db_drop_primary_key($table) {
./core/includes/database.inc:function db_add_unique_key($table, $name, $fields) {
./core/includes/database.inc:function db_drop_unique_key($table, $name) {
./core/includes/database.inc:function db_drop_index($table, $name) {
./core/includes/database.inc: * db_drop_primary_key('foo');
./core/lib/Drupal/Core/Database/Schema.php:   * db_drop_primary_key('foo');
./core/lib/Drupal/Core/Database/Query/TableSortExtender.php:      // Based on code from db_escape_table(), but this can also contain a dot.

So there are a couple of comments in Schema.php and TableSortExtender.php to be fixed, too.

NW to add tests as per #5.

1. +++ b/core/includes/database.inc
   @@ -364,6 +364,7 @@ function db_set_active($key = 'default') {
   +  @trigger_error('db_escape_table() is deprecated in Drupal 8.0.x and will be removed before Drupal 9.0.0. Instead, get a database connection injected into your service from the container and call escapeTable() on it. For example, $injected_database->escapeTable($table). See https://www.drupal.org/node/2993033.', E_USER_DEPRECATED);
   

   Pls remove the final dot from the message string, see #2848137-66: Replace all calls to db_update, which is deprecated, also in the other methods and the corresponding tests,

2. +++ b/core/tests/Drupal/KernelTests/Core/Database/DatabaseLegacyTest.php
   @@ -206,4 +206,90 @@ public function testDbMerge() {
   +  public function testDbDriver() {
   +    $this->assertTrue(db_driver());
   +  }
   

   assertNotNull, the function returns a string

3. +++ b/core/tests/Drupal/KernelTests/Core/Database/DatabaseLegacyTest.php
   @@ -206,4 +206,90 @@ public function testDbMerge() {
   +  public function testDbEscapeField() {
   +    $this->assertTrue(db_escape_field('test'));
   +  }
   

   same

4. +++ b/core/tests/Drupal/KernelTests/Core/Database/DatabaseLegacyTest.php
   @@ -206,4 +206,90 @@ public function testDbMerge() {
   +  public function testDbEscapeTable() {
   +    $this->assertTrue(db_escape_table('test'));
   +  }
   

   same

5. +++ b/core/tests/Drupal/KernelTests/Core/Database/DatabaseLegacyTest.php
   @@ -206,4 +206,90 @@ public function testDbMerge() {
   +  public function testDbDropIndex() {
   +    $schema = drupal_get_module_schema('database_test', 'test');
   +    $this->connection->schema()->addIndex('test', 'job', ['job'], $schema);
   +    $this->assertTrue(db_drop_index('test', 'job'));
   +  }
   

   it's sufficient to assertFalse on dropping a non-existent index

+++ b/core/tests/Drupal/KernelTests/Core/Database/DatabaseLegacyTest.php
@@ -208,6 +208,92 @@ public function testDbMerge() {
+  public function testDbDropIndex() {
+    $schema = drupal_get_module_schema('database_test', 'test');
+    $this->connection->schema()->addIndex('test', 'job', ['job'], $schema);
+    $this->assertFalse(db_drop_index('test', 'job'));
+  }

just:

  public function testDbDropIndex() {
    $this->assertFalse(db_drop_index('test', 'no_such_index'));
  }

Please add interdiffs when posting new patches on top of previous ones.

LGTM, thank you