[FEATURE] Enhance LDAP/SMTP TLS Configuration and Unify Them (#1557)

* add new directive in the global scope `certificates_directory` which is used to bulk load certs and trust them in Authelia
* this is in ADDITION to system certs and are trusted by both LDAP and SMTP
* added a shared TLSConfig struct to be used by both SMTP and LDAP, and anything else in the future that requires tuning the TLS
* remove usage of deprecated LDAP funcs Dial and DialTLS in favor of DialURL which is also easier to use
* use the server name from LDAP URL or SMTP host when validating the certificate unless otherwise defined in the TLS section
* added temporary translations from the old names to the new ones for all deprecated options
* added docs
* updated example configuration
* final deprecations to be done in 4.28.0
* doc updates
* fix misc linting issues
* uniform deprecation notices for ease of final removal
* added additional tests covering previously uncovered areas and the new configuration options
* add non-fatal to certificate loading when system certs could not be loaded
* adjust timeout of Suite ShortTimeouts
* add warnings pusher for the StructValidator
* make the schema suites uninform
* utilize the warnings in the StructValidator
* fix test suite usage for skip_verify
* extract LDAP filter parsing into it's own function to make it possible to test
* test LDAP filter parsing
* update ErrorContainer interface
* add tests to the StructValidator
* add NewTLSConfig test
* move baseDN for users/groups into parsed values
* add tests to cover many of the outstanding areas in LDAP
* add explicit deferred LDAP conn close to UpdatePassword
* add some basic testing to SMTP notifier
* suggestions from code review

1 files changed, 16 insertions, 12 deletions

diff --git a/internal/configuration/schema/notifier.go b/internal/configuration/schema/notifier.go
index b3817c8ce..58c5428c6 100644
--- a/internal/configuration/schema/notifier.go
+++ b/internal/configuration/schema/notifier.go
@@ -7,18 +7,19 @@ type FileSystemNotifierConfiguration struct {
 
 // SMTPNotifierConfiguration represents the configuration of the SMTP server to send emails with.
 type SMTPNotifierConfiguration struct {
-	Host                string `mapstructure:"host"`
-	Port                int    `mapstructure:"port"`
-	Username            string `mapstructure:"username"`
-	Password            string `mapstructure:"password"`
-	Identifier          string `mapstructure:"identifier"`
-	Sender              string `mapstructure:"sender"`
-	Subject             string `mapstructure:"subject"`
-	TrustedCert         string `mapstructure:"trusted_cert"`
-	StartupCheckAddress string `mapstructure:"startup_check_address"`
-	DisableVerifyCert   bool   `mapstructure:"disable_verify_cert"`
-	DisableRequireTLS   bool   `mapstructure:"disable_require_tls"`
-	DisableHTMLEmails   bool   `mapstructure:"disable_html_emails"`
+	Host                string     `mapstructure:"host"`
+	Port                int        `mapstructure:"port"`
+	Username            string     `mapstructure:"username"`
+	Password            string     `mapstructure:"password"`
+	Identifier          string     `mapstructure:"identifier"`
+	Sender              string     `mapstructure:"sender"`
+	Subject             string     `mapstructure:"subject"`
+	StartupCheckAddress string     `mapstructure:"startup_check_address"`
+	DisableRequireTLS   bool       `mapstructure:"disable_require_tls"`
+	DisableHTMLEmails   bool       `mapstructure:"disable_html_emails"`
+	TLS                 *TLSConfig `mapstructure:"tls"`
+	TrustedCert         string     `mapstructure:"trusted_cert"`        // Deprecated: Replaced with Global Option CertificatesDirectory. TODO: Remove in 4.28.
+	DisableVerifyCert   *bool      `mapstructure:"disable_verify_cert"` // Deprecated: Replaced with LDAPAuthenticationBackendConfiguration.TLS.SkipVerify. TODO: Remove in 4.28.
 }
 
 // NotifierConfiguration represents the configuration of the notifier to use when sending notifications to users.
@@ -32,4 +33,7 @@ type NotifierConfiguration struct {
 var DefaultSMTPNotifierConfiguration = SMTPNotifierConfiguration{
 	Subject:    "[Authelia] {title}",
 	Identifier: "localhost",
+	TLS: &TLSConfig{
+		MinimumVersion: "TLS1.2",
+	},
 }