fix(tray): do not abort on a malformed orders entry - #5296

What does this PR do?

Host's config parsing asserts that every value in orders is an integer:

assert(value.isInt());
orders_[key] = value.asInt();

Waybar builds with b_ndebug=false, so the assert is live in release builds
too. A single typo in a user's config takes down the whole bar with no
actionable message:

$ waybar -c bad.json
[info] Tray: No ignore-list configured
waybar: ../src/modules/sni/host.cpp:39: waybar::modules::SNI::Host::Host(...): Assertion `value.isInt()' failed.
[1]    core dumped

Reproducer:

"tray": { "orders": { "gammastep": "oops" } }

This skips the offending entry with a warning instead, and checks that orders
is an object before iterating it. User input should not be able to terminate
waybar.

After:

[warning] tray: ignoring order for 'gammastep': expected an integer

Related issues

None. Found while working on #4162 / #5297; independent of both.

Checklist

• Code is formatted with clang-format
• Builds locally (ninja -C build)
• Man page updated for any new/changed user-facing option (man/) — n/a, no config surface changes
• Tested against the affected module(s) — tray, with a valid config, a
  non-integer value, and orders set to a non-object