Detect when there is no .zshrc file and create it if necessary

[natesilva]

When installing on a Mac that does not have a .zshrc file yet, Eclectica fails with an error:

% ec -r node@12

langauge: node 
 version: 12.16.1 

> open : no such file or directory

I had this happen when using Eclectica to install Node on a new Mac that I hadn’t configured yet.

Workaround

Create a .zshrc file first:

% touch ~/.zshrc

% ec -r node@12 

langauge: node 
 version: 12.16.1 

> First time executing eclectica - had to restart the shell

Environment

macOS 10.15.3 (where zsh is now the default shell)
Eclectica 0.7.1

[markelog]

Okay, seems easy enough to fix