Pyroscope Process Lifecycle Refactoring

[petethepig]

• move to cobra
• standardize Exec functions in cli package
• remove Cli related things from domain packages
• move flags stuff to a separate package
• move Server / Agent / Convert configs out of config package
• split configs between CLI / domain logic
• get rid of global logger
• do more tests for cli interface

[petethepig]

Some of it was done in #300