Added debug log for install script output

[ethunk]

I ran into issues with installing vector and in order to debug it I needed to see the output of the install script. This will by default print the output of the vector install script for help with debugging.

One idea is to check first for MIX_DEBUG environment variable and only log if MIX_DEBUG=true | 1

I tested this locally by running on jetstream and updating the vector install file in the deps folder

mix deps.compile vector_agent --force  

Example of error state:

mix deps.compile vector_agent --force                       [6:30:20]
==> vector_agent
06:30:21.479 [debug] Vector binary downloading...
                                   __   __  __
                                   \ \ / / / /
                                    \ V / / /
                                     \_/  \/

                                   V E C T O R
                                    Installer


--------------------------------------------------------------------------------
Website: https://vector.dev
Docs: https://vector.dev/docs/
Community: https://vector.dev/community/
--------------------------------------------------------------------------------

>>> Downloading Vector via https://packages.timber.io/vector/0.42.0/vector-0.42.0-arm64-apple-darwin.tar.gzcurl: (56) The requested URL returned error: 404
vector: installer for platform 'aarch64-apple-darwin' not found, this may be unsupported


== Compilation error in file lib/vector/installer.ex ==
** (RuntimeError) Vector binary failed to install.
    lib/vector/installer.ex:78: Vector.Installer.validate!/1
    (stdlib 6.2) lists.erl:2146: :lists.foldl/3

Example of a successful install:

mix deps.compile vector_agent --force
==> vector_agent
Compiling 8 files (.ex)

06:35:32.243 [debug] Vector binary downloading...

06:35:37.269 [debug] Vector 0.44.0 installed.
Generated vector_agent app