[Feature:Developer] Allow customization of VM resources (#11922)

### Why is this Change Important & Necessary?
<!-- Include any GitHub issue that is fixed/closed using "Fixes
#<number>" or "Closes #<number>" syntax.
Alternately write "Partially addresses #<number>" or "Related to
#<number>" as appropriate. -->
Currently whenever `vagrant up` is run the VM is created with 2G of ram
and 2 cpus.

### What is the New Behavior?
<!-- Include before & after screenshots/videos if the user interface has
changed. -->
This adds two new environment variables that can be used to configure
the values for the vm. An example of both of them used is
`VM_MEMORY=4096 VM_CPUS=4 vagrant up`

### What steps should a reviewer take to reproduce or test the bug or
new feature?
1. Run `vagrant up` and observe the memory and cpus allocated to your
vm.
2. Run `vagrant halt && vagrant up` with `VM_CPUS` and/or `VM_MEMORY`
set and verify the correct value is used.

### Automated Testing & Documentation
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tests?
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new GitHub issue and link it below.
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documentation added in PR:
Submitty/submitty.github.io#695

### Other information
<!-- Is this a breaking change?  
Does this PR include migrations to update existing installations?  
Are there security concerns with this PR? -->

Author: lavalleeale

Vagrantfile

@@ -7,6 +7,8 @@
 #   NO_SUBMISSIONS=1 vagrant up
 #       or
 #   EXTRA=rpi vagrant up
+#       or
+#   VM_MEMORY=4096 VM_CPUS=4 vagrant up
 #
 #
 # If you want to override the default image used for the virtual machines, you can set the
@@ -25,6 +27,9 @@
 #
 # If you don't want any submissions to be automatically generated for the courses created
 # by vagrant, you'll want to specify NO_SUBMISSIONS flag.
+#
+# You can also customize VM resources using environment variables:
+# VM_MEMORY=4096 VM_CPUS=4 vagrant up
 
 # Don't buffer output.
 $stdout.sync = true
@@ -34,6 +39,10 @@ require 'json'
 
 ON_CI = !ENV.fetch('CI', '').empty?
 
+# VM resource configuration
+VM_MEMORY = ENV.fetch('VM_MEMORY', ON_CI ? '1024' : '2048').to_i
+VM_CPUS = ENV.fetch('VM_CPUS', ON_CI ? '1' : '2').to_i
+
 def gen_script(machine_name, worker: false, base: false)
   no_submissions = !ENV.fetch('NO_SUBMISSIONS', '').empty?
   reinstall = ENV.has_key?('VAGRANT_BOX') || base
@@ -197,8 +206,8 @@ Vagrant.configure(2) do |config|
 
     # We limit resources when running on CI to avoid resource exhaustion and it isn't used for grading stuff or
     # other things we do in dev.
-    vb.memory = ON_CI ? 1024 : 2048
-    vb.cpus = ON_CI ? 1 : 2
+    vb.memory = VM_MEMORY
+    vb.cpus = VM_CPUS
 
     # When you put your computer (while running the VM) to sleep, then resume work some time later the VM will be out
     # of sync timewise with the host for however long the host was asleep. Of course, the VM by default will
@@ -243,8 +252,8 @@ Vagrant.configure(2) do |config|
       end
     end
 
-    prl.memory = 2048
-    prl.cpus = 2
+    prl.memory = VM_MEMORY
+    prl.cpus = VM_CPUS
 
     mount_folders(override, ["share", "nosuid"])
   end
@@ -255,8 +264,8 @@ Vagrant.configure(2) do |config|
         override.vm.box = base_boxes[:arm_bento]
       end
     end
-    vmware.vmx["memsize"] = "2048"
-    vmware.vmx["numvcpus"] = "2"
+    vmware.vmx["memsize"] = VM_MEMORY.to_s
+    vmware.vmx["numvcpus"] = VM_CPUS.to_s
 
     mount_folders(override, [])
   end
@@ -268,8 +277,8 @@ Vagrant.configure(2) do |config|
 
     libvirt.qemu_use_session = true
 
-    libvirt.memory = 2048
-    libvirt.cpus = 2
+    libvirt.memory = VM_MEMORY
+    libvirt.cpus = VM_CPUS
 
     libvirt.forward_ssh_port = true
 
@@ -283,8 +292,8 @@ Vagrant.configure(2) do |config|
       end
     end
 
-    qe.memory = "2G"
-    qe.smp = 2
+    qe.memory = "#{VM_MEMORY}M"
+    qe.smp = VM_CPUS
   end
 
   config.vm.provision :shell, :inline => " sudo timedatectl set-timezone America/New_York", run: "once"