MM-25731 Advanced Logging (#14888)

Adds Advanced Logging to server. Advanced Logging is an optional logging capability that allows customers to send log records to any number of destinations.

Supported destinations:
- file
- syslog (with out without TLS)
- raw TCP socket (with out without TLS)

Allows developers to specify discrete log levels as well as the standard trace, debug, info, ... panic. Existing code and logging API usage is unchanged.

Log records are emitted asynchronously to reduce latency to the caller. Supports hot-reloading of logger config, including adding removing targets.

Advanced Logging is configured within config.json via "LogSettings.AdvancedLoggingConfig" which can contain a filespec to another config file, a database DSN, or JSON.

go.mod

@@ -43,7 +43,7 @@ require (
 	github.com/hashicorp/go-hclog v0.14.1
 	github.com/hashicorp/go-immutable-radix v1.2.0 // indirect
 	github.com/hashicorp/go-msgpack v1.1.5 // indirect
-	github.com/hashicorp/go-multierror v1.1.0 // indirect
+	github.com/hashicorp/go-multierror v1.1.0
 	github.com/hashicorp/go-plugin v1.3.0
 	github.com/hashicorp/go-sockaddr v1.0.2 // indirect
 	github.com/hashicorp/go-uuid v1.0.1 // indirect
@@ -63,6 +63,7 @@ require (
 	github.com/mattermost/gorp v2.0.1-0.20200527092429-d62b7b9cadfc+incompatible
 	github.com/mattermost/gosaml2 v0.3.2
 	github.com/mattermost/ldap v0.0.0-20191128190019-9f62ba4b8d4d
+	github.com/mattermost/logr v1.0.5
 	github.com/mattermost/rsc v0.0.0-20160330161541-bbaefb05eaa0
 	github.com/mattermost/viper v1.0.4
 	github.com/mattn/go-colorable v0.1.7 // indirect
@@ -108,7 +109,6 @@ require (
 	github.com/uber/jaeger-client-go v2.24.0+incompatible
 	github.com/uber/jaeger-lib v2.2.0+incompatible
 	github.com/vmihailenco/msgpack/v5 v5.0.0-beta.1
-	github.com/wiggin77/logr v1.0.4
 	github.com/wiggin77/merror v1.0.2
 	github.com/wiggin77/srslog v1.0.1
 	github.com/xtgo/uuid v0.0.0-20140804021211-a0b114877d4c // indirect