Configuring aliases in bashrc with guix home

["Brennan Vincent" <brennan@umanwizard.com>]

Hello,

By default, the `home-bash-service-type` creates a .bashrc with the
default bashrc (defined in %default-bashrc in gnu/system/shadow.scm),
followed by user-defined aliases, followed by a user-defined bashrc
file.

The problem is that %default-bashrc already contains some aliases:

alias ls='ls -p --color=auto'
alias ll='ls -l'
alias grep='grep --color=auto'
alias ip='ip -color=auto'

which makes it difficult for the user to manage her own set of
aliases. If the user wants to remove all the aliases from
%default-bashrc and set her own, she can run `unalias -a` in her own
bashrc first. But then she can't use the user-defined aliases mechanism
from home-bash-configuration, since that is added to the file before the
user-defined bashrc.

My suggestion is that when aliases is set in home-bash-configuration, we
remove the predefined default aliases from %default-bashrc. Or at least
provide an option to do so.