fix(diagnostic): display 1-based related information line/col numbers (#37093)

Problem
LSP Related Information line and column numbers are 0-based. Displaying
them this way can confuse the user, since vim line/col numbers are
typically displayed 1-based.

Solution
Display the line and column numbers as 1-based.

test/functional/lua/diagnostic_spec.lua

@@ -3559,8 +3559,8 @@ describe('vim.diagnostic', function()
       eq(
         {
           '1. Some warning',
-          '   uri:1:0: Some extra info',
-          '   uri:2:3: Some more extra info',
+          '   uri:2:1: Some extra info',
+          '   uri:3:4: Some more extra info',
         },
         exec_lua(function()
           ---@type vim.Diagnostic