feat: support custom_lua_shared_dict in global lua {} block and stream {} block

[houtengfei193-spec]

What this PR does

Currently, custom_lua_shared_dict only works in the http {} block (added in #5030). This PR extends the same mechanism to:

1. The global lua {} block (requires apisix-nginx-module) — for shared dicts accessible by both HTTP and Stream subsystems
2. The stream {} block — for stream-only shared dicts

Why

Users who need cross-subsystem shared dicts (e.g., for lifecycle management, custom metrics, global state sharing) currently have to manually patch ngx_tpl.lua. This PR allows them to simply configure it in config.yaml:

nginx_config:
  meta:
    custom_lua_shared_dict:
      my-global-dict: 1m       # shared between http and stream
  stream:
    custom_lua_shared_dict:
      my-stream-dict: 5m       # stream only

Changes

File	Change
apisix/cli/ngx_tpl.lua	Add dynamic rendering loop in lua {} and stream {} blocks
apisix/cli/config.lua	Add default empty custom_lua_shared_dict for meta and stream
apisix/cli/schema.lua	Add schema validation for meta and stream custom_lua_shared_dict
t/cli/test_custom_shared_dict.sh	Test cases covering meta, stream, combined, and empty configs

Backward Compatibility

100% backward compatible. Default custom_lua_shared_dict is an empty table — no behavior change without explicit configuration.

Note: The meta.custom_lua_shared_dict feature only takes effect when apisix-nginx-module is compiled in (i.e., use_apisix_base is true), since the global lua {} block itself is only rendered in that case.

[houtengfei193-spec]

Hi @nic-6443 @shreemaan-abhishek, could you help approve the CI workflow for this PR? It's a small change (size:M) extending custom_lua_shared_dict to support stream {} and global lua {} blocks. Thanks!

[houtengfei193-spec]

@membphis @tzssangglass @spacewander

Could you please review this PR? All CI checks have passed.

This PR adds support for custom_lua_shared_dict in:

• Global lua {} block (for sharing between HTTP and Stream subsystems)
• stream {} block (for Stream-only dictionaries)

This resolves the need to manually modify ngx_tpl.lua when users need cross-subsystem shared dictionaries (e.g., for lifecycle management, custom metrics, global state sharing).

All 18 CI checks have passed (1 skipped for DockerHub build which is expected for PRs).

Thank you for your time and review!