ojo_connect overhaul #190

Overarching Goal:

• Create an ojo_connect function that can either be used invisibly as the default argument to the db connection argument of ojo_tbl or ojo_query, OR be used with no side-effects to create a connection object that can be passed around manually
• Connect by default to our Postgres db but alternatively to other backends like duckdb
• Integrate with ojo_auth for auth related config values
• Be able to create a connection pool for when used programatically in an environment like R Shiny or highly parallel code with transactions

Currently, ojo_connect:

• Creates a connection type string (ojo_pool or ojo_con) based on arguments
• Creates a connection key using connection type and the DBI driver name passed to the .driver arg, e.g. RPostgres
• Creates a connection args variable which is a list of connection arguments
  • Switches list depending on the backend
  • Aborts if driver is an unsupported one
• Programatically passes the args list to the appropriate connection function using rlang::exec and !!!
• Assigns the connection object to a variable named after the connection key in the environment specified by the .env argument, defaulting to the global environment
• If the driver is duckdb:
  • Installs needed plugins like httpfs and sets s3_endpoints to google cloud storage
• Launches a withr deferred statement in the environment where the connection was created that closes the connection when that environment shuts down

It tries to, but doesn't succeed in:

• Distinguishing between admin and default accounts, limiting access type or impersonating roles as needed
• Allowing for local, side-effect free assignment of connection object with no deferred connection closing

It needs to:

• Achieve overarching goals
• Be highly modular and future-proofed for new backends
• Use the implementation of ojo_auth in the ojodb-v3 and connect branches

It maybe shouldn't:

• Try to do too many things without breaking into sub functions

It maybe could:

• Have breaking changes to clean up function signature
• Use classed list arguments whose values are provided using a function of the same name as the argument
  • Like ojo_auth does with db_config = db_config(...) or bslib does with navbar_options = navbar_options(...)