Add support for verible: language server + fixer (#4994)

* Add support for verible: language server + fixer
* verible: add default flag, rules support for verible-ls

ale_linters/verilog/verible_ls.vim

@@ -0,0 +1,43 @@
+" Author: Nicolas Derumigny <https://github.com/nicolasderumigny>
+" Description: Verible LSP for verilog
+
+call ale#Set('verilog_verible_ls_options', '--rules_config_search')
+call ale#Set('verilog_verible_ls_rules', '')
+call ale#Set('verilog_verible_ls_executable', 'verible-verilog-ls')
+call ale#Set('verilog_verible_ls_config', {})
+
+function! ale_linters#verilog#verible_ls#GetProjectRoot(buffer) abort
+    let l:git_dir = ale#path#FindNearestFile(a:buffer, 'verible.filelist')
+
+    if !empty(l:git_dir)
+        return fnamemodify(l:git_dir, ':p:h')
+    else
+        return fnamemodify('', ':h')
+    endif
+endfunction
+
+function! ale_linters#verilog#verible_ls#GetCommand(buffer) abort
+    let l:command = ale#Escape(ale#Var(a:buffer, 'verilog_verible_ls_executable'))
+    let l:options = ale#Var(a:buffer, 'verilog_verible_ls_options')
+    let l:rules = ale#Var(a:buffer, 'verilog_verible_ls_rules')
+
+    if l:options isnot# ''
+        let l:command .= ' ' . l:options
+    endif
+
+    if l:rules isnot# ''
+        let l:command .= ' --rules=' . l:rules
+    endif
+
+    return l:command
+endfunction
+
+
+call ale#linter#Define('verilog', {
+\   'name': 'verible_ls',
+\   'lsp': 'stdio',
+\   'lsp_config': {b -> ale#Var(b, 'verilog_verible_ls_config')},
+\   'executable': {b -> ale#Var(b, 'verilog_verible_ls_executable')},
+\   'command': function('ale_linters#verilog#verible_ls#GetCommand') ,
+\   'project_root': function('ale_linters#verilog#verible_ls#GetProjectRoot'),
+\})