Warn via FES when bezierOrder() receives a value other than 2 or 3

[harshiltewari2004]

Resolves #9079

Changes

bezierOrder() is documented as accepting 2 or 3 but validated nothing, so
out-of-range values reached the renderers and failed differently in each:
2D drew nothing, WebGL silently reinterpreted the shape as a quadratic, and
bezierOrder(1) threw a TypeError from inside p5.

fn.bezierOrder now emits a non-blocking FES warning when the order isn't
2 or 3. Renderer behaviour is unchanged — this only adds a message.

Per @davepagurek's preference on the issue, the check reads
p5.disableFriendlyErrors first, so a sketch with FES turned off does no
further work. order !== undefined is checked next so the getter form
(bezierOrder() with no argument) doesn't warn.

Non-numeric and non-integer values ('3', 2.5, null) also warn, since
they fail the same comparison.

The order-1 TypeError still occurs after the warning; the warning names
bezierOrder first, so the user sees the cause before the crash.

PR Checklist

• npm run lint passes
• [Inline reference] is included / updated
• [Unit tests] are included / updated