workstation: add crystal and shards

Add the crystal programming language along with its package manager
shards.

manifests/workstation.pp

@@ -32,6 +32,7 @@ class freebsd::workstation inherits freebsd::base {
       'codeblocks',
       'conky',
       'cowsay',
+      'crystal',
       'cscope',
       'curl',
       'darkice',
@@ -144,6 +145,7 @@ class freebsd::workstation inherits freebsd::base {
       'rxvt-unicode',
       'scons-py37',
       'scrot',
+      'shards',
       'siril',
       'source-highlight',
       'sqlite',