Add self update feature with GUI

[kevinchua6]

Uses the https://github.com/creativeprojects/go-selfupdate package to detect updates and automatically self-updates when the app is started, prompting a restart.

Example:

Fixes #50

[Beebeeoii]

thanks for making this PR. looks good ! just some additional thoughts regarding this feature: would it be better to:

• have this checking for update run on daily cron instead of just on startup?
• have a check for update button somewhere (possibly in preferences) for users to check for updates immediately?
• have a "auto update checkbox" for users to indicate if they want the app to auto update?

[kevinchua6]

1. I think it's only necessary to do it on startup, because we need to restart the app anyway after updating. It's also not a very costly operation in terms of time taken haha so I don't think there's much advantage of doing it on cron
2. I think that's a good idea! I'll implement this.
3. Good idea! I'll do this also

[Beebeeoii]

works fine on windows but something seems off when i tested this on kubuntu 22.04... looks like its something to do with permissions.

[2022-08-09 22:47:51] FATAL - Error occurred while updating binary: open /usr/local/bin/.lominus.new: permission denied (/home/jiawei/Documents/lominus/internal/app/updater/updater.go:github.com/beebeeoii/lominus/internal/app/updater.DoSelfUpdate:43)

would guess that it does not have the permissions to create .lominus.new?

[Beebeeoii]

ill go ahead and close this PR as it is all merged into feat-auto-update and pending PR #81 into development. thank you so much !