Mono repo -> Master (#22553)

Combines the following repositories into one:

https://github.com/mattermost/mattermost-server
https://github.com/mattermost/mattermost-webapp
https://github.com/mattermost/focalboard
https://github.com/mattermost/mattermost-plugin-playbooks

server/platform/shared/driver/driver.go

@@ -0,0 +1,57 @@
+// Copyright (c) 2015-present Mattermost, Inc. All Rights Reserved.
+// See LICENSE.txt for license information.
+
+// package driver implements a DB driver that can be used by plugins
+// to make SQL queries using RPC. This helps to avoid opening new connections
+// for every plugin, and lets everyone use the central connection
+// pool in the server.
+// The tests for this package are at app/plugin_api_tests/test_db_driver/main.go.
+package driver
+
+import (
+	"context"
+	"database/sql/driver"
+
+	"github.com/mattermost/mattermost-server/v6/plugin"
+)
+
+var (
+	// Compile-time check to ensure Connector implements the interface.
+	_ driver.Connector = &Connector{}
+)
+
+// Connector is the DB connector which is used to
+// communicate with the DB API.
+type Connector struct {
+	api      plugin.Driver
+	isMaster bool
+}
+
+// NewConnector returns a DB connector that can be used to return a sql.DB object.
+// It takes a plugin.Driver implementation and a boolean flag to indicate whether
+// to connect to a master or replica DB instance.
+func NewConnector(api plugin.Driver, isMaster bool) *Connector {
+	return &Connector{api: api, isMaster: isMaster}
+}
+
+func (c *Connector) Connect(_ context.Context) (driver.Conn, error) {
+	connID, err := c.api.Conn(c.isMaster)
+	if err != nil {
+		return nil, err
+	}
+
+	return &Conn{id: connID, api: c.api}, nil
+}
+
+func (c *Connector) Driver() driver.Driver {
+	return &Driver{c: c}
+}
+
+// Driver is a DB driver implementation.
+type Driver struct {
+	c *Connector
+}
+
+func (d Driver) Open(name string) (driver.Conn, error) {
+	return d.c.Connect(context.Background())
+}