Refactor: install.conf.yaml shell commands configuration

[yasinmiran]

Describe the suggestion

Currently, we repeat the dotbot's shell configs in every instruction.

dotfiles_macos/install.conf.yaml

Lines 21 to 33 in b8d9db1

	- shell:
	- command: ./setup_homebrew.zsh
	stdout: true
	stderr: true
	- command: ./setup_zsh.zsh
	stdout: true
	stderr: true
	- command: ./setup_node.zsh
	stdout: true
	stderr: true
	- command: ./setup_macos.zsh
	stdout: true
	stderr: true

Describe the improvement

We can simply add them to dotbot's default configurations to prevent duplication. Like the following: -

- defaults:
    shell:
      stdout: true
      stderr: true

What if one of them is different?

If want to override these configurations at some point, say i.e., turn off stderr for a specific shell command (let's say setup_node script), we can simply add the same configuration as we used to do. When dotbot sees this it will turn off
stderr when running setup_node.

- command: ./setup_node.zsh
  stderr: false 

[WhatsThatItsPat]

I like it, Yasin. I'll accept the PR after I've had a chance to think about what kind of lesson I can make from this.