Fix ale#lsp#message#* to convert column to 0-based

This is what LSP specifies.

autoload/ale/lsp/message.vim

@@ -3,6 +3,10 @@
 "
 " Messages in this movie will be returned in the format
 " [is_notification, method_name, params?]
+"
+" All functions which accept line and column arguments expect them to be 1-based
+" (the same format as being returned by getcurpos() and friends), those then
+" will be converted to 0-based as specified by LSP.
 let g:ale_lsp_next_version_id = 1
 
 " The LSP protocols demands that we send every change to a document, including
@@ -98,7 +102,7 @@ function! ale#lsp#message#Completion(buffer, line, column, trigger_character) ab
     \   'textDocument': {
     \       'uri': ale#path#ToURI(expand('#' . a:buffer . ':p')),
     \   },
-    \   'position': {'line': a:line - 1, 'character': a:column},
+    \   'position': {'line': a:line - 1, 'character': a:column - 1},
     \}]
 
     if !empty(a:trigger_character)
@@ -116,7 +120,7 @@ function! ale#lsp#message#Definition(buffer, line, column) abort
     \   'textDocument': {
     \       'uri': ale#path#ToURI(expand('#' . a:buffer . ':p')),
     \   },
-    \   'position': {'line': a:line - 1, 'character': a:column},
+    \   'position': {'line': a:line - 1, 'character': a:column - 1},
     \}]
 endfunction
 
@@ -125,7 +129,7 @@ function! ale#lsp#message#References(buffer, line, column) abort
     \   'textDocument': {
     \       'uri': ale#path#ToURI(expand('#' . a:buffer . ':p')),
     \   },
-    \   'position': {'line': a:line - 1, 'character': a:column},
+    \   'position': {'line': a:line - 1, 'character': a:column - 1},
     \   'context': {'includeDeclaration': v:false},
     \}]
 endfunction
@@ -141,7 +145,7 @@ function! ale#lsp#message#Hover(buffer, line, column) abort
     \   'textDocument': {
     \       'uri': ale#path#ToURI(expand('#' . a:buffer . ':p')),
     \   },
-    \   'position': {'line': a:line - 1, 'character': a:column},
+    \   'position': {'line': a:line - 1, 'character': a:column - 1},
     \}]
 endfunction