feat: allow toggling of instrumentations via env vars

[seemk]

Allow toggling instrumentations as is done in the Java instrumentation.

• New environment variable OTEL_INSTRUMENTATION_COMMON_DEFAULT_ENABLED (default: true). When set to false, prevents the loading of all embedded (the ones we ship with the distro) instrumentations. This can be used to selectively switch on instrumentations, e.g. OTEL_INSTRUMENTATION_COMMON_DEFAULT_ENABLED=false OTEL_INSTRUMENTATION_PG_ENABLED=true will only enable pg instrumentation.

• New environment variables with the pattern OTEL_INSTRUMENTATION_[NAME]_ENABLED, where [NAME] is the instrumentation name (see the below table). E.g. OTEL_INSTRUMENTATION_PG_ENABLED=false will just disable pg instrumentation.

⚠️ This only applies to instrumentations loaded by default in our distribution, when using the programmatic API to supply a list of user-specified instrumentations, it will have no effect.

All environment variables are case-insensitive, i.e. OTEL_INSTRUMENTATION_pg_ENABLED is the same as OTEL_INSTRUMENTATION_PG_ENABLED.

Instrumentation	Environment variable name
@opentelemetry/instrumentation-amqplib	amqplib
@opentelemetry/instrumentation-aws-sdk	aws_sdk
@opentelemetry/instrumentation-bunyan	bunyan
@opentelemetry/instrumentation-cassandra-driver	cassandra_driver
@opentelemetry/instrumentation-connect	connect
@opentelemetry/instrumentation-dataloader	dataloader
@opentelemetry/instrumentation-dns	dns
@opentelemetry/instrumentation-express	express
@opentelemetry/instrumentation-fastify	fastify
@opentelemetry/instrumentation-generic-pool	generic_pool
@opentelemetry/instrumentation-graphql	graphql
@opentelemetry/instrumentation-grpc	grpc
@opentelemetry/instrumentation-hapi	hapi
@opentelemetry/instrumentation-http	http
@opentelemetry/instrumentation-ioredis	ioredis
@opentelemetry/instrumentation-knex	knex
@opentelemetry/instrumentation-koa	koa
@opentelemetry/instrumentation-memcached	memcached
@opentelemetry/instrumentation-mongodb	mongodb
@opentelemetry/instrumentation-mongoose	mongoose
@opentelemetry/instrumentation-mysql	mysql
@opentelemetry/instrumentation-mysql2	mysql2
@opentelemetry/instrumentation-nestjs-core	nestjs_core
@opentelemetry/instrumentation-net	net
@opentelemetry/instrumentation-pg	pg
@opentelemetry/instrumentation-pino	pino
@opentelemetry/instrumentation-redis	redis
@opentelemetry/instrumentation-redis-4	redis_4
@opentelemetry/instrumentation-restify	restify
@opentelemetry/instrumentation-router	router
@opentelemetry/instrumentation-tedious	tedious
@opentelemetry/instrumentation-winston	winston
elasticsearch	elasticsearch
kafkajs	kafkajs
sequelize	sequelize
typeorm	typeorm