Add plugin for pipenv (#6698)

- Add completion for pipenv
- Auto activate and deactivate for pipenv shell
- Add aliases for the most common pipenv commands

plugins/pipenv/README.md

@@ -0,0 +1,28 @@
+# Pipenv
+
+## Installation
+In your `.zshrc` file, add `pipenv` to the plugins section
+
+```
+plugins=(... pipenv ...)
+```
+
+## Features
+This plugin provides some features to simplify the use of Pipenv while working on ZSH. 
+- Adds completion for pipenv
+- Auto activates and deactivates pipenv shell
+- Adds short aliases for common pipenv commands
+  - `pch` is aliased to `pipenv check`
+  - `pcl` is aliased to `pipenv clean`
+  - `pgr` is aliased to `pipenv graph`
+  - `pi` is aliased to `pipenv install`
+  - `pidev` is aliased to `pipenv install --dev`
+  - `pl` is aliased to `pipenv lock`
+  - `po` is aliased to `pipenv open`
+  - `prun` is aliased to `pipenv run`
+  - `psh` is aliased to `pipenv shell`
+  - `psy` is aliased to `pipenv sync`
+  - `pu` is aliased to `pipenv uninstall`
+  - `pwh` is aliased to `pipenv --where`
+  - `pvenv` is aliased to `pipenv --venv`
+  - `ppy` is aliased to `pipenv --py`