Semantic constants for db.system

[trask]

Does it make sense have semantic constants somewhere for db.system? based on the spec table https://github.com/open-telemetry/opentelemetry-specification/blob/master/specification/trace/semantic_conventions/database.md

Value	Description
other_sql	Some other SQL database. Fallback only. See notes.
mssql	Microsoft SQL Server
mysql	MySQL
oracle	Oracle Database
db2	IBM Db2
postgresql	PostgreSQL
redshift	Amazon Redshift
hive	Apache Hive
cloudscape	Cloudscape
hsqlsb	HyperSQL DataBase
progress	Progress Database
maxdb	SAP MaxDB
hanadb	SAP HANA
ingres	Ingres
firstsql	FirstSQL
edb	EnterpriseDB
cache	InterSystems Caché
adabas	Adabas (Adaptable Database System)
firebird	Firebird
derby	Apache Derby
filemaker	FileMaker
informix	Informix
instantdb	InstantDB
interbase	InterBase
mariadb	MariaDB
netezza	Netezza
pervasive	Pervasive PSQL
pointbase	PointBase
sqlite	SQLite
sybase	Sybase
teradata	Teradata
vertica	Vertica
h2	H2
coldfusion	ColdFusion IMQ
cassandra	Apache Cassandra
hbase	Apache HBase
mongodb	MongoDB
redis	Redis
couchbase	Couchbase
couchdb	CouchDB
cosmosdb	Microsoft Azure Cosmos DB
dynamodb	Amazon DynamoDB
neo4j	Neo4j

[thisthat]

I'll propose a way to generate them automatically from the YAML definitions :)