Cleanup: Remove unnecessary intermediate variables

[1ambd4]

What type of PR is this?

• cleanup

What this PR does / why we need it:

In the initial version of the code, Commands is of type []Command.

https://github.com/urfave/cli/blob/aced6e8739166ac46d05f741f60891d3cf2331e9/app.go#L25

In this case iterating over Commands using range will generate intermediate variables, so it needs to be written as follows

https://github.com/urfave/cli/blob/aced6e8739166ac46d05f741f60891d3cf2331e9/app.go#L90-L95

But this part of the code has changed in the last decade. Now, Commands is of type []*Command and, in my opinion, there is no need to manipulate intermediate variables.

https://github.com/urfave/cli/blob/7656c5fb838ca8a6febca43100147d317b544fd3/app.go#L54

https://github.com/urfave/cli/blob/7656c5fb838ca8a6febca43100147d317b544fd3/app.go#L232-L244

The same reason is true for the removal of code in cli/command.go.

https://github.com/urfave/cli/blob/aced6e8739166ac46d05f741f60891d3cf2331e9/command.go#L34

https://github.com/urfave/cli/blob/aced6e8739166ac46d05f741f60891d3cf2331e9/command.go#L197-L202

https://github.com/urfave/cli/blob/7656c5fb838ca8a6febca43100147d317b544fd3/command.go#L42

https://github.com/urfave/cli/blob/7656c5fb838ca8a6febca43100147d317b544fd3/command.go#L135-L143

Special notes for your reviewer:

I'm not familiar with the Go language, so please point out any errors in my understanding, and thanks for reviewing.

Release Notes

NONE