tools.vpm: improve prints for install command

[ttytm]

• Improves the feedback messages that are printed during installation.

  E.g. currently all this is printed in non-verbose mode, when installing a module.

  ❯ v install https://github.com/vlang/markdow
  Installing module "markdown" from "https://github.com/vlang/markdown" to "/home/t/.vmodules/vlang/markdown" ...
  Relocating module from "vlang/markdown" to "markdown" ("/home/t/.vmodules/markdown") ...
  Warning module "/home/t/.vmodules/markdown" already exists!
  Removing module "/home/t/.vmodules/markdown" ...
  Module "markdown" relocated to "markdown" successfully.
  

  But when using --once, the already installed info would only be printed with the verbose flag added. Without it, the install command would immediately finish, without printing any info.

  ❯ v install -v --once https://github.com/vlang/markdown.git
  Already installed modules: ['markdown']
  All modules are already installed.
  ╭─ ~/Dev/vlang/v
  ╰─❯ ▌
  
  # Current no verbose (no feedback)
  ❯ v install --once https://github.com/vlang/markdown.git
  ╭─ ~/Dev/vlang/v
  ╰─❯ ▌
  
  
  # PR no verbose
  ❯ v install --once https://github.com/vlang/markdown.git
  All modules are already installed.
  ╭─ ~/Dev/vlang/v
  ╰─❯ ▌
  

  With the PR the the All modules are already installed. info is printed also in non-verbose mode. I think giving the short feedback to the users is useful also here to confirm that their request was processed.

• Removes some info from verbose mode that is imho only relevant for debugging and not for the user. E.g.

  ❯ v install --once -v https://github.com/vlang/markdown.git
  - cli params: ['install', 'https://github.com/vlang/markdown.git']
  -      command: git --version
  -      command: git clone --depth=1 --recursive --shallow-submodules "https://github.com/vlang/markdown.git" "/home/t/.vmodules/vlang/markdown.git"
  ...

[spytheman]

That is useful for debugging problems when the main v executable invokes the vpm tool.
I would prefer if it stays, but you can wrap it in something like if os.getenv('VPM_DEBUG') != '' { if you like.

[ttytm]

Yes, definitely useful for debugging as mentioned. I left it as a comment where this is more apparent. The idea with the debug env var is great. When the simple version-installs are finished I'll add it. We could use the log package for it and set the log level to debug when the env var is passed. Would that fit here?