Refactor authentication as plugin, in order to add MariaDB parsec and PAM authentication + permit multiple authentication switch.

multiple authentication switch are permit in MariaDB using OR (https://mariadb.com/kb/en/create-user/#identified-viawith-authentication_plugin) and in MySQL using multi authenticator (https://dev.mysql.com/doc/refman/8.0/en/multifactor-authentication.html)

Author: rusher

.github/workflows/test.yml

@@ -39,6 +39,7 @@ jobs:
               '8.4', # LTS
               '8.0',
               '5.7',
+              'mariadb-11.7',   # in order to test parsec
               'mariadb-11.4',   # LTS
               'mariadb-11.2',
               'mariadb-11.1',

AUTHORS

@@ -37,6 +37,7 @@ Daniel Montoya <dsmontoyam at gmail.com>
 Daniel Nichter <nil at codenode.com>
 Daniël van Eeden <git at myname.nl>
 Dave Protasowski <dprotaso at gmail.com>
+Diego Dupin <diego.dupin at gmail.com>
 Dirkjan Bussink <d.bussink at gmail.com>
 DisposaBoy <disposaboy at dby.me>
 Egor Smolyakov <egorsmkv at gmail.com>

README.md

@@ -172,6 +172,16 @@ Default:        false
 
 `allowCleartextPasswords=true` allows using the [cleartext client side plugin](https://dev.mysql.com/doc/en/cleartext-pluggable-authentication.html) if required by an account, such as one defined with the [PAM authentication plugin](http://dev.mysql.com/doc/en/pam-authentication-plugin.html). Sending passwords in clear text may be a security problem in some configurations. To avoid problems if there is any possibility that the password would be intercepted, clients should connect to MySQL Server using a method that protects the password. Possibilities include [TLS / SSL](#tls), IPsec, or a private network.
 
+##### `AllowDialogPasswords`
+
+```
+Type:           bool
+Valid Values:   true, false
+Default:        false
+```
+
+`AllowDialogPasswords=true` allows using the [PAM client side plugin](https://mariadb.com/kb/en/authentication-plugin-pam/) if required by an account, such as one defined with the PAM authentication plugin. Sending passwords in clear text may be a security problem in some configurations. To avoid problems if there is any possibility that the password would be intercepted, clients should connect to Server using a method that protects the password. Possibilities include [TLS / SSL](#tls), IPsec, or a private network.
+
 
 ##### `allowFallbackToPlaintext`
 
@@ -453,6 +463,16 @@ Default:        none
 
 [Connection attributes](https://dev.mysql.com/doc/refman/8.0/en/performance-schema-connection-attribute-tables.html) are key-value pairs that application programs can pass to the server at connect time.
 
+
+##### `OtherPasswd`
+
+```
+Type:           comma-delimited string of password for MariaDB PAM authentication, if requiring more than one password
+Valid Values:   (<password2>,<password3>,...)
+Default:        none
+```
+
+
 ##### System Variables
 
 Any other parameters are interpreted as system variables:
@@ -534,6 +554,19 @@ See [context support in the database/sql package](https://golang.org/doc/go1.8#d
 > The `QueryContext`, `ExecContext`, etc. variants provided by `database/sql` will cause the connection to be closed if the provided context is cancelled or timed out before the result is received by the driver.
 
 
+### Authentication Plugin System
+
+The driver implements a pluggable authentication system that supports various authentication methods used by MySQL and MariaDB servers. The built-in authentication plugins include:
+
+- `mysql_native_password` - The default MySQL authentication method
+- `caching_sha2_password` - Default authentication method in MySQL 8.0+
+- `mysql_clear_password` - Cleartext authentication (requires `allowCleartextPasswords=true`)
+- `mysql_old_password` - Old MySQL authentication (requires `allowOldPasswords=true`)
+- `sha256_password` - SHA256 authentication
+- `parsec` - MariaDB 11.6+ PARSEC authentication
+- `client_ed25519` - MariaDB Ed25519 authentication
+- `dialog` - MariaDB PAM authentication  (requires `AllowDialogPasswords=true`)
+
 ### `LOAD DATA LOCAL INFILE` support
 For this feature you need direct access to the package. Therefore you must change the import path (no `_`):
 ```go