Support for LSP/tsserver Code Actions (#3437)

* Added tsserver and LSP code action support.
* tsserver refactors support added.
* Handling special case when new text is added after new line symbol.
* ale#code_action#ApplyChanges simplified.
* Initial attempt on LSP Code Actions.
* workspace/executeCommand added.
* Some null checks added.
* Add last column to LSP Code Action message.
* Pass diagnostics to LSP code action.

Previously ApplyChanges code was applied from top-to-bottom that required 
extra parameters to track progress and there was bug. I have changed code
to bottom-to-top approach as that does not require those extra parameters
and solved the bug.

Tested with typescript-language-server and it is working.

ale_linters/python/jedils.vim

@@ -0,0 +1,34 @@
+" Author: Dalius Dobravolskas <dalius.dobravolskas@gmail.com>
+" Description: https://github.com/pappasam/jedi-language-server
+
+call ale#Set('python_jedils_executable', 'jedi-language-server')
+call ale#Set('python_jedils_use_global', get(g:, 'ale_use_global_executables', 0))
+call ale#Set('python_jedils_auto_pipenv', 0)
+
+function! ale_linters#python#jedils#GetExecutable(buffer) abort
+    if (ale#Var(a:buffer, 'python_auto_pipenv') || ale#Var(a:buffer, 'python_jedils_auto_pipenv'))
+    \ && ale#python#PipenvPresent(a:buffer)
+        return 'pipenv'
+    endif
+
+    return ale#python#FindExecutable(a:buffer, 'python_jedils', ['jedi-language-server'])
+endfunction
+
+function! ale_linters#python#jedils#GetCommand(buffer) abort
+    let l:executable = ale_linters#python#jedils#GetExecutable(a:buffer)
+
+    let l:exec_args = l:executable =~? 'pipenv$'
+    \   ? ' run jedi-language-server'
+    \   : ''
+
+    return ale#Escape(l:executable) . l:exec_args
+endfunction
+
+call ale#linter#Define('python', {
+\   'name': 'jedils',
+\   'lsp': 'stdio',
+\   'executable': function('ale_linters#python#jedils#GetExecutable'),
+\   'command': function('ale_linters#python#jedils#GetCommand'),
+\   'project_root': function('ale#python#FindProjectRoot'),
+\   'completion_filter': 'ale#completion#python#CompletionItemFilter',
+\})