Add support for configuring global, user, & workspace options

[MulverineX]

sand options [-g|--global|-u|--user] set <command> <option> [<value>]

Ordered by priority:

• user options - <working dir>/sandstone.user.config.ts - .gitignore'd local options
• workspace options - <working dir>/sandstone.config.ts - existing config
• global options - <TBD dir>/sandstone.global.config.ts - persistent global options