[linter] Add LSP support for LaTeX via texlab

ale_linters/tex/texlab.vim

@@ -0,0 +1,21 @@
+" Author: Ricardo Liang <ricardoliang@gmail.com>
+" Description: Texlab language server (Rust rewrite)
+
+call ale#Set('tex_texlab_executable', 'texlab')
+call ale#Set('tex_texlab_options', '')
+
+function! ale_linters#tex#texlab#GetProjectRoot(buffer) abort
+    return ''
+endfunction
+
+function! ale_linters#tex#texlab#GetCommand(buffer) abort
+    return '%e' . ale#Pad(ale#Var(a:buffer, 'tex_texlab_options'))
+endfunction
+
+call ale#linter#Define('tex', {
+\   'name': 'texlab',
+\   'lsp': 'stdio',
+\   'executable': {b -> ale#Var(b, 'tex_texlab_executable')},
+\   'command': function('ale_linters#tex#texlab#GetCommand'),
+\   'project_root': function('ale_linters#tex#texlab#GetProjectRoot'),
+\})