Refactoring

[ChrisTerBeke]

What

• Refactored the codebase to resolve some issues with weird (and near cyclic) dependencies
• Created a store package that groups all logic around the file system operations
• Re-named download to client and merged it with HTTP logic for listing versions
• De-duplicated code where possible
• Moved some code into functions so that the name can be used as self documentation (reduces need for inline comments)
• Removed nested statements where possible
• Added early returns where possible
• Removed github.com/tfversion from the internal package name
• Fixed some edge cases around listing and deleting aliases

All commands now only import their corresponding package or the helpers. All packages now only import client, helpers or store, with the exception of use -> install for the auto install feature.

Why

• Better readability and maintainability

[mmourick]

LGTM 🗿