add a new toolkit install command with --features support (#9288)

# Description
i was installing Nushell and, as we have the `dataframe` feature and
very soon at least the `extra` feature with more and more commands, i
thought it could be cool to have a little `toolkit install` command
😋

# User-Facing Changes
exposes the following command to developers
```
install Nushell and features you want

Usage:
  > install ...(features) 

Flags:
  -h, --help - Display the help message for this command

Parameters:
  ...features <string>: a space-separated list of feature to install with Nushell
```

# Tests + Formatting
- 🟢 `toolkit fmt`
- 🟢 `toolkit clippy`
- ⚫ `toolkit test`
- ⚫ `toolkit test stdlib`

# After Submitting
```
$nothing
```

scripts/build-all.nu

@@ -1,7 +1,11 @@
+use std log warning
+
 print '-------------------------------------------------------------------'
 print 'Building nushell (nu) with dataframes and all the plugins'
 print '-------------------------------------------------------------------'
 
+warning "./scripts/build-all.nu will be deprecated, please use the `toolkit build` command instead"
+
 let repo_root = ($env.CURRENT_FILE | path dirname -n 2)
 
 def build-nushell [] {

scripts/coverage-local.nu

@@ -1,4 +1,7 @@
 #!/usr/bin/env nu
+use std log warning
+
+warning "./scripts/coverage-local.nu will be deprecated, please use the `toolkit cov` command instead"
 
 def compute-coverage [] {
     cd ($env.CURRENT_FILE | path dirname -n 2)

scripts/register-plugins.nu

@@ -1,3 +1,7 @@
+use std log warning
+
+warning "./scripts/register-plugin.nu will be deprecated, please use the `toolkit plugin register` command instead"
+
 # are we on windows or not?
 def windows? [] {
     $nu.os-info.name == windows