gopls: add go_gopls_init_options

ale_linters/go/gopls.vim

@@ -4,6 +4,7 @@
 
 call ale#Set('go_gopls_executable', 'gopls')
 call ale#Set('go_gopls_options', '--mode stdio')
+call ale#Set('go_gopls_init_options', {})
 
 function! ale_linters#go#gopls#GetCommand(buffer) abort
     return ale#go#EnvString(a:buffer)
@@ -31,4 +32,5 @@ call ale#linter#Define('go', {
 \   'executable': {b -> ale#Var(b, 'go_gopls_executable')},
 \   'command': function('ale_linters#go#gopls#GetCommand'),
 \   'project_root': function('ale_linters#go#gopls#FindProjectRoot'),
+\   'initialization_options': {b -> ale#Var(b, 'go_gopls_init_options')},
 \})