runtime(thrift): add ftplugin, indent and syntax scripts

Problem: Apache Thrift files misses ftplugin, indent and syntax scripts

Solution:
- add ftplugin and indent scripts
- add thrift indent test
- port the syntax script from apache/thrift (Apache License 2)

Reference:
https://diwakergupta.github.io/thrift-missing-guide/#_language_reference

closes: #15387

Signed-off-by: Yinzuo Jiang <jiangyinzuo@foxmail.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>

runtime/indent/thrift.vim

@@ -0,0 +1,74 @@
+" Vim indent file
+" Language: Apache Thrift
+" Maintainer: Yinzuo Jiang <jiangyinzuo@foxmail.com>
+" Last Change: 2024/07/29
+
+" Only load this indent file when no other was loaded.
+if exists("b:did_indent")
+  finish
+endif
+let b:did_indent = 1
+
+setlocal cindent
+setlocal indentexpr=GetThriftIndent()
+
+let b:undo_indent = "set cindent< indentexpr<"
+
+" Only define the function once.
+if exists("*GetThriftIndent")
+  finish
+endif
+
+let s:keepcpo= &cpo
+set cpo&vim
+
+function! SkipThriftBlanksAndComments(startline)
+  let lnum = a:startline
+  while lnum > 1
+    let lnum = prevnonblank(lnum)
+    if getline(lnum) =~ '\*/\s*$'
+      while getline(lnum) !~ '/\*' && lnum > 1
+        let lnum = lnum - 1
+      endwhile
+      if getline(lnum) =~ '^\s*/\*'
+        let lnum = lnum - 1
+      else
+        break
+      endif
+    elseif getline(lnum) =~ '^\s*\(//\|#\)'
+      let lnum = lnum - 1
+    else
+      break
+    endif
+  endwhile
+  return lnum
+endfunction
+
+function GetThriftIndent()
+  " Thrift is just like C; use the built-in C indenting and then correct a few
+  " specific cases.
+  let theIndent = cindent(v:lnum)
+
+  " If we're in the middle of a comment then just trust cindent
+  if getline(v:lnum) =~ '^\s*\*'
+    return theIndent
+  endif
+
+  let line = substitute(getline(v:lnum), '\(//\|#\).*$', '', '')
+  let previousNum = SkipThriftBlanksAndComments(v:lnum - 1)
+  let previous = substitute(getline(previousNum), '\(//\|#\).*$', '', '')
+
+  let l:indent = indent(previousNum)
+  if previous =~ "{" && previous !~ "}"
+    let l:indent += shiftwidth()
+  endif
+  if line =~ "}" && line !~ "{"
+    let l:indent -= shiftwidth()
+  endif
+  return l:indent
+endfunction
+
+let &cpo = s:keepcpo
+unlet s:keepcpo
+
+" vim: sw=2 sts=2 et