runtime(hcl,terraform): Add runtime files for HCL and Terraform

closes: #15618

Signed-off-by: Gregory Anders <greg@gpanders.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>
diff --git a/runtime/autoload/hcl.vim b/runtime/autoload/hcl.vim
new file mode 100644
index 0000000..2215fc8
--- /dev/null
+++ b/runtime/autoload/hcl.vim
@@ -0,0 +1,40 @@
+" Language:    HCL
+" Maintainer:  Gregory Anders
+" Last Change: 2024-09-03
+" Based on:    https://github.com/hashivim/vim-terraform
+
+function! hcl#indentexpr(lnum)
+  " Beginning of the file should have no indent
+  if a:lnum == 0
+    return 0
+  endif
+
+  " Usual case is to continue at the same indent as the previous non-blank line.
+  let prevlnum = prevnonblank(a:lnum-1)
+  let thisindent = indent(prevlnum)
+
+  " If that previous line is a non-comment ending in [ { (, increase the
+  " indent level.
+  let prevline = getline(prevlnum)
+  if prevline !~# '^\s*\(#\|//\)' && prevline =~# '[\[{\(]\s*$'
+    let thisindent += &shiftwidth
+  endif
+
+  " If the current line ends a block, decrease the indent level.
+  let thisline = getline(a:lnum)
+  if thisline =~# '^\s*[\)}\]]'
+    let thisindent -= &shiftwidth
+  endif
+
+  " If the previous line starts a block comment /*, increase by one
+  if prevline =~# '/\*'
+    let thisindent += 1
+  endif
+
+  " If the previous line ends a block comment */, decrease by one
+  if prevline =~# '\*/'
+    let thisindent -= 1
+  endif
+
+  return thisindent
+endfunction