fix(ssh): compare table length in the SSH config #41637

Problem:
`parse_ssh_config()` compares tables against a freshly allocated empty
table.
- In `parse_multiple_values()`, the guard which avoids flushing an empty
  accumulator never applies. Runs of separators and trailing whitespace
  push empty strings into the results, and `is_valid()` does not filter
  them. `Host  alpha   beta ` parses as `{ 'alpha', '', 'beta' }`.
- In `parse_value()`, the condition reduces to `chr == '"' and quoted`.
  `quoted` starts false and only that branch sets it, so it can never
  become true: quotes are never recognised and are inserted literally,
  and the unterminated-quote check is unreachable.

Solution:
Compare `#val` instead. Add a test for repeated and trailing separators.

AI-assisted

test/functional/lua/ssh_spec.lua

@@ -49,6 +49,18 @@ describe('SSH parser', function()
     }, parser.parse_ssh_config(config))
   end)
 
+  it('ignores repeated and trailing separators', function()
+    -- Runs of separators between values, and trailing whitespace before the
+    -- line break, must not yield empty hostnames.
+    local config = table.concat({
+      'Host  alpha   beta ',
+      '  HostName example.com',
+      '',
+    }, '\n')
+
+    eq({ 'alpha', 'beta' }, parser.parse_ssh_config(config))
+  end)
+
   it('fails when a quote is not closed', function()
     local config = [[
       Host prod dev "test prod my