runtime(terraform): Add filetype plugin for terraform

- Adds commentstring property for terraform
- Adds comments property for terraform

closes: #15144

Co-authored-by: zeertzjq <zeertzjq@outlook.com>
Signed-off-by: Janno Tjarks <janno.tjarks@mailbox.org>
Signed-off-by: Christian Brabandt <cb@256bit.org>

runtime/ftplugin/terraform.vim

@@ -0,0 +1,14 @@
+" Vim filetype plugin
+" Language: terraform
+" Maintainer: Janno Tjarks (janno.tjarks@mailbox.org)
+" Last Change: 2024 Jul 3
+
+if exists('b:did_ftplugin')
+  finish
+endif
+let b:did_ftplugin = 1
+
+setlocal commentstring=#\ %s
+setlocal comments=://,:#
+
+let b:undo_ftplugin = "setlocal commentstring< comments<"