Migrate CI/CD pipelines

[achrinza]

With the shift of the LoopBack project to the OpenJS Foundation, the CI/CD pipelines are being shifted away from IBM-owned Travis infrastructure to a combination of GitHub Actions, Travis CI, and AppVeyor.

This issue is used to provide a consolidated view of this progress.

The migration status is also being tracked at https://github.com/achrinza/loopback-framework-ci-status (among other things).

Repos:

• loopback-next
• loopback4-example-shopping
• loopback-connector
• loopback-connector-cassandra
• loopback-connector-cloudant
• loopback-connector-couchdb2
• loopback-connector-db2
• loopback-connector-dashdb
• loopback-connector-elastic-search
• loopback-connector-grpc
• loopback-connector-ibmi
• loopback-connector-kv-extreme-scale
• loopback-connector-kv-redis
• loopback-connector-mongodb
  • v6.x
  • v5.x
• loopback-connector-mysql
• loopback-connector-openapi
• loopback-connector-oracle
• loopback-connector-postgresql
• loopback-connector-redis
• loopback-connector-rest
• loopback-connector-soap
• loopback-connector-sqlite3
• loopback-datasource-juggler
• loopback-extension-grpc
• loopback-ibmdb
• strong-soap