Add update command to the CLI

[autodidaddict]

Proposed change

Run nex update and it will automatically update the nex binary.

Use case

For people who don't like having to remember what toolchain they used to install a given binary (was it brew? apt? nix? asdf? curl?), it just makes life so much easier if we can do nex update and have it update to the latest version. note that this just applies to replacing the binary being run, and doesn't affect a running process

Contribution

No response

[jordan-rash]

I had this on my todo list... thanks for making the issue

[jordan-rash]

Stage 1 complete: #174

[autodidaddict]

For clarity this issue remains open as the nex update functionality hasn't been created yet

[jordan-rash]

Stage 2 complete: #200

Last piece missing is to add some logic around what happens if you update the binary with a node running

[jordan-rash]

Satisfied by #174 and #200