refactor: ✨ (#418)

* refactor: ✨ move in one commit

Eveything in modules should probably be changed to `exported` defs.
The idea is to move everything first to keep proper history.

* refactor: 📝 add modules readme (wip)

* refactor: ✨ small move

* refactor: 📝 changed nestring, updated modules readme

* refactor: 📝 to document or not to document

* fix: 🐛 themes

replaced the template to use `main` and regenerated them
from lemnos themes.

* Revert "fix: 🐛 themes"

This reverts commit 4918d3633c8d2d81950a0ed0cfd9eb84241bc886.

* refactor: ✨ introduce sourced

- Created a source `root` in which sourcable demos are stored.
  Some might get converted to modules later on.
- Moved some files to bin too.

* fix: 🐛 fehbg.nu

* fix: 🐛 modules/after.nu

* moved some other stuff around

---------

Co-authored-by: Darren Schroeder <343840+fdncred@users.noreply.github.com>

modules/virtual_environments/nu_msvs/README.md

@@ -0,0 +1,43 @@
+# MSVS Module for Nushell
+A module for Using Microsoft Visual Studio (MSVS) command line tools from Nushell.
+
+
+## Prerequisites
+- [nushell](https://github.com/nushell/nushell) >= 0.73.0
+- [vswhere](https://github.com/microsoft/vswhere) standalone or comes with VS
+
+
+## Installation
+Put `nu_msvs.nu` into the module folder of your nushell configuration workspace.
+
+
+## Usage
+```nu
+use nu_msvs.nu
+nu_msvs activate  # Use 'nu_msvs activate --help' to see all available options
+nu_msvs deactivate
+```
+
+
+## How It Works
+MSVS provides scripts (such as `vsdevcmd.bat` and `vsvarsall.bat`) for
+developers to use its command line tools (such as `cl.exe`) in Command Prompt
+and Powershell, but these scripts are not available for nushell. One method to
+use MSVS command line tools in nushell was described in nushell/nushell#5803,
+which requires launching nushell within an Command Prompt/Powershell instance.
+However, running `vsdevcmd.bat` or launching Powershell is quite slow.
+Therefore, `nu_msvs.nu` is introduced and works similar to a virtual
+environment.
+
+When activating the MSVS environment (take MSVC tools for example):
+1. Necessary path are added to `PATH`/`Path` to allow command line tools (e.g.
+`cl.exe`) to be run in nushell.
+2. An environment variable `INCLUDE` is defined and consists of Win32 header
+directories, which will be used by `cl.exe`.
+3. An environment variable `LIB` is defined and consists of Win32 library
+directories, which will be used by `link.exe`.
+
+
+## Supported Tools
+- [x] MSVC
+- [ ] ...