Add regression tests for lua support

Change Dockerfile to install lua, luajit and love and also to install
nodejs 12 needed to build the lua debug adapter. Create the
love-headless test in support/test/lua to test love without an x server.

tests/language_lua.test.vim

@@ -0,0 +1,84 @@
+function! SetUp()
+  let g:vimspector_enable_mappings = 'HUMAN'
+  call vimspector#test#setup#SetUpWithMappings( v:none )
+endfunction
+
+function! ClearDown()
+  call vimspector#test#setup#ClearDown()
+endfunction
+
+
+function! BaseTest( configuration )
+  let fn='simple.lua'
+  lcd ../support/test/lua/simple
+  exe 'edit ' . fn
+
+  call vimspector#SetLineBreakpoint( fn, 9 )
+  call vimspector#LaunchWithSettings( { 'configuration': a:configuration } )
+
+  " This debugger is ignoring stopOnEntry when not running a custom executable
+  " and always stopping on the first line after setting the hook. This first
+  " check assumes that behavior.
+  call vimspector#test#signs#AssertCursorIsAtLineInBuffer( fn, 5, 1 )
+  call WaitForAssert( {->
+        \ vimspector#test#signs#AssertPCIsAtLineInBuffer( fn, 5 )
+        \ } )
+  " Continue
+  call feedkeys( "\<F5>", 'xt' )
+
+  call vimspector#test#signs#AssertCursorIsAtLineInBuffer( fn, 9, 1 )
+  call WaitForAssert( {->
+        \ vimspector#test#signs#AssertPCIsAtLineInBuffer( fn, 9 )
+        \ } )
+
+  " Step
+  call feedkeys( "\<F10>", 'xt' )
+
+  call vimspector#test#signs#AssertCursorIsAtLineInBuffer( fn, 10, 1 )
+  call WaitForAssert( {->
+        \ vimspector#test#signs#AssertPCIsAtLineInBuffer( fn, 10 )
+        \ } )
+
+  call vimspector#test#setup#Reset()
+
+  lcd -
+  %bwipeout!
+endfunction
+
+
+function! Test_Lua_Simple()
+  call BaseTest( 'lua' )
+endfunction
+
+
+function! Test_Lua_Luajit()
+  call BaseTest( 'luajit' )
+endfunction
+
+
+function! Test_Lua_Love()
+  let fn='main.lua'
+  lcd ../support/test/lua/love-headless
+  exe 'edit ' . fn
+
+  call vimspector#SetLineBreakpoint( fn, 8 )
+  call vimspector#LaunchWithSettings( { 'configuration': 'love' } )
+
+  call vimspector#test#signs#AssertCursorIsAtLineInBuffer( fn, 8, 1 )
+  call WaitForAssert( {->
+        \ vimspector#test#signs#AssertPCIsAtLineInBuffer( fn, 8 )
+        \ } )
+
+  " Step
+  call feedkeys( "\<F10>", 'xt' )
+
+  call vimspector#test#signs#AssertCursorIsAtLineInBuffer( fn, 9, 1 )
+  call WaitForAssert( {->
+        \ vimspector#test#signs#AssertPCIsAtLineInBuffer( fn, 9 )
+        \ } )
+
+  call vimspector#test#setup#Reset()
+
+  lcd -
+  %bwipeout!
+endfunction