Fix update notifier usage to support yarn

[vgrichina]

No description provided.

[mikedotexe]

I had a hard time understanding what this is doing, since I don't see updateCommand anywhere and there's no description here. So I hacked it so it'll output it, hardcoding version 9.1.0 and this is what I get:

We don't want this, right? We're telling people to install near-shell globally with npm everywhere, but this will just add the latest version locally with yarn correct?

[vgrichina]

@mikedotexe it is context-sensitive. If you install near-shell using npm – it'll output command for npm. You can test it like this:

1. Change package.json version to 0.23.2-foobar
2. npm i -g .
3. you need to run some command 2 times (check is cached), then you'll get a banner:

   ╭──────────────────────────────────────────────────────────────────╮
   │                                                                  │
   │   NEAR Shell has a prerelease available 0.23.2-foobar → 0.23.2   │
   │    Run npm install -g near-shell to avoid unexpected behavior    │
   │                                                                  │
   ╰──────────────────────────────────────────────────────────────────╯

We hardcoded npm specifically for some reason which was giving incorrect message when installed with yarn, using local version from project, etc. This brings it back to how update-notifier package is designed.

[mikedotexe]

Okay, I see it working as I'd hoped by doing:
npm i near-shell@0.23.1 -g
and then a couple times until it clicked:
near state mike.testnet

[vgrichina]

Okay, I see it working as I'd hoped by doing:
npm i near-shell@0.23.1 -g
and then a couple times until it clicked:
near state mike.testnet

this tests near-shell@0.23.1, not this PR

[mikedotexe]

Jeez, I'm jumping around too much today and tested that in a silly way.
So I think this is still problematic @vgrichina

   │                                                          │
   │     NEAR Shell has a patch available 0.22.0 → 0.23.2     │
   │   Run yarn add near-shell to avoid unexpected behavior   │
   │                                                          │
   ╰──────────────────────────────────────────────────────────╯

But when I run this command:

yarn global v1.22.4
info "create-near-app@0.9.3" has binaries:
   - create-near-app
✨  Done in 0.17s.

it's not in the global for yarn. So this banner is essentially telling me to add yarn locally.
I'm using nvm btw.