Fix EA Post Grid | Polylang: translate saved templates & pin Post Grid query language

[ZebaAfiaShama]

Saved templates embedded in EA widgets (Advanced Tabs, Advanced Accordion, Info Box, Flip Box, CTA Box, Countdown, Data Table) always rendered the source-language template on Polylang sites, and Post Grids could show posts from the wrong language.

Root causes:

• Template translation used post type 'wp_template'; EA saved templates are 'elementor_library', so the wpml_object_id lookup never matched and returned the original id unchanged.
• Polylang ships no Elementor integration, so elementor_library is not a translatable post type and the central documents/get/post_id translation filter was disabled (gated to WPML only).
• Post Grid query had no language pinning, so it followed the ambient (cookie / last-page-load) language instead of the page's own language.

Fixes:

• Correct post type 'wp_template' -> 'elementor_library' in all saved-template wpml_object_id calls.
• Make eael_wpml_template_translation() Polylang-native via pll_get_post(), and re-enable the elementor/documents/get/post_id filter for Polylang.
• Register elementor_library as translatable via pll_get_post_types.
• Pin the Post Grid query to the page/document language (new Helper::eael_get_current_language()), with an eael/post_grid/query_lang filter.
• Add a language suffix to Post Grid transient cache keys to avoid collisions between translated pages that share a widget id.