Refactor commands into separate modules

[chshersh]

Some refactoring to change a few things:

• Move all commands into separate modules to make the top-level match in lib.rs concise
• Change the text of the default-config
• Refactor formatting of tool names into a separate function
• Rename integration test files to specify whether they are used for the the sync or install command

[MitchellBerend]

Maybe this is just me but I like having the line start with the #, this is obviously preference though.

# This configuration is automatically generated by tool-sync 0.1.0
# https://github.com/chshersh/tool-sync
#######################################
#
# Installation directory for all the tools:
# store_directory = "$HOME/.local/bin"
#
# tool-sync provides native support for some of the tools without the need to
# configure them. Uncomment all the tools you want to install with a single
# 'tool sync' command:
#
# [bat]
# [difftastic]
# [exa]
# [fd]
# [ripgrep]
# [tool-sync]
#
# You can configure the installation of any tool by specifying corresponding options:
#
# [ripgrep]  # Name of the tool (new or one of the hardcoded to override default settings)
#     owner     = "BurntSushi"  # GitHub repository owner
#     repo      = "ripgrep"     # GitHub repository name
#     exe_name  = "rg"          # Executable name inside the asset

#     Uncomment to download a specific version or tag.
#     Without this tag latest will be used
#     tag       = "13.0.0"

#     Asset name to download on linux OSes
#     asset_name.linux = "x86_64-unknown-linux-musl"

#     Uncomment if you want to install on macOS as well
#     asset_name.macos = "apple-darwin"

#     Uncomment if you want to install on Windows as well
#     asset_name.windows = "x86_64-pc-windows-msvc"

[chshersh]

Maybe this is just me but I like having the line start with the #, this is obviously preference though.

I don't might changing the format actually. I don't have strong feelings about one or another. Having all the comments as leading comments makes it look more consistent 👍🏻