[Config] Dynamically enable/disable instrumentations

[jackshirazi]

Is your feature request related to a problem?

Required feature

Describe the solution you'd like

Each instrumentation can individually be enabled/disabled

Describe alternatives you've considered

• most likely we'll use scoped tracers
• removing instrumentations completely and (re)installing. Some instrumentations need to be installed at agent start, and others don't play nicely with being removed and then installed
• catching spans as they're created or exported and setting them as non-sampled - but the context isn't properly available

Additional context

The classic agent disable_instrumentations