[Feature] Validate config.yaml at the end of alpine edit

[maxzinkus]

To make alpine edit more useful, at the end, it should do a quick parse & validate of the config.yaml file(s) which were edited and relay a message about their validity, erroring if one or more are invalid:

0. malformed YAML
1. alias is invalid
2. image not found in ~/.macpine/cache or not on filesystem
3. arch not one of aarch64 or x86_64
4. cpu not a positive integer
5. memory not a positive integer >= 256
6. disk not a valid size
7. mount not a directory on the host
8. port string invalid
9. sshport not a positive integer
10. location not correct (~/.macpine/instance-name matching alias)

• 0 can be checked with the yaml library
• 1 can be checked with cmd/rename.go:100 validateName(...)
• 2-9 can be checked with cmd/launch.go:46 correctArguments(...)
• 10 can be checked manually

[maxzinkus]

I'll pick this one up :)

[maxzinkus]

#149 is ready for review @idroz ! :)