Refactor Shell. Remove ShellOut.

[albertodebortoli]

This PR initially aimed to remove ShellOut in favour of Apple's TSCBasic but I couldn't wrap my head around it without first reworking Shell.

• Refactor Shell to have a clearer interface that only wraps the underlying shell from TSCBasic (e.g. avoid duplication of Process)
• Remove logger from Shell (it has stdout and stderr and best to leave print statements at the call sites to avoid mixing responsibilities)
• Move commands out of Shell to Shell+Commands to have clear responsibilities
• Remove which and downloadResource commands as they are unused. They seem to be leftovers from Added StellarEnv to manage and communicate with stellar installed versions #24.
• Split into more files: ShellError and ProcessResult+Throwing
• Remove usage of sudo as not needed (/usr/local/bin is writable without sudo) and wasn't working (it exits the program as needs user input)
• Reorganise some files on disk
• Remove ShellOut in favour of Apple's TSCBasic

[albertodebortoli]

Ok chaps, sorted by reintroducing @malcommac's code :)

[Stellar] Expanding the archive…
[Stellar] Installing at /usr/local/bin/stellarenv…
rm: /usr/local/bin/stellarenv: Permission denied
Password:
mv: rename /var/folders/7s/4wmmddq506gbsdvlr53sd0lh0000gn/T/com.stellarenv-D36BF29A-8BE8-47F5-93AC-C69008AA72C1/StellarEnv to /usr/local/bin/stellarenv: Permission denied
[Stellar] StellarEnv version 0.0.8 installed
[Stellar] Stellar version 0.0.8 installed

I tried on a different mac where my user is in the wheel group (see https://superuser.com/questions/20420/what-is-the-difference-between-the-default-groups-on-mac-os-x). I'm still not clear on the details of user management in unix but frankly I'm not interested now. ChatGPT will teach me anyway next time I need this :)

I've also added the shared schemes for StellarEnv.

[malcommac]

👍