Add explicit lifetimes to fix `mismatched_lifetime_syntaxes` warnings

[gsokoll]

Description

Recent versions of Rust have enabled the mismatched_lifetime_syntaxes lint by default. This produces warnings when &self implies a lifetime but the return type uses elision to hide it. The current codebase generates 16 such warnings during compilation.

Example warning

warning: hiding a lifetime that's elided elsewhere is confusing
   --> rclrs/src/client.rs:423:15
    |
423 |     fn handle(&self) -> RclPrimitiveHandle {
    |               ^^^^^     ^^^^^^^^^^^^^^^^^^ the same lifetime is hidden here
    |               |
    |               the lifetime is elided here
    |
    = help: the same lifetime is referred to in inconsistent ways, making the signature confusing
help: use `'_` for type paths
    |
423 |     fn handle(&self) -> RclPrimitiveHandle<'_> {
    |                                           ++++

Affected locations

File	Function	Current	Should Be
action/action_client.rs:850	handle()	RclPrimitiveHandle	RclPrimitiveHandle<'_>
action/action_client.rs:866	lock()	MutexGuard<rcl_action_client_t>	MutexGuard<'_, rcl_action_client_t>
action/action_server.rs:665	handle()	RclPrimitiveHandle	RclPrimitiveHandle<'_>
action/action_server.rs:690	lock()	MutexGuard<rcl_action_server_t>	MutexGuard<'_, rcl_action_server_t>
action/action_server/action_server_goal_handle.rs:34	lock()	MutexGuard<rcl_action_goal_handle_t>	MutexGuard<'_, rcl_action_goal_handle_t>
client.rs:423	handle()	RclPrimitiveHandle	RclPrimitiveHandle<'_>
client.rs:546	lock()	MutexGuard<rcl_client_t>	MutexGuard<'_, rcl_client_t>
logging/log_params.rs:39	get_logger_name()	&LoggerName	&LoggerName<'_>
node.rs:1244	use_undeclared_parameters()	Parameters	Parameters<'_>
service.rs:268	handle()	RclPrimitiveHandle	RclPrimitiveHandle<'_>
service.rs:288	lock()	MutexGuard<rcl_service_t>	MutexGuard<'_, rcl_service_t>
subscription.rs:280	handle()	RclPrimitiveHandle	RclPrimitiveHandle<'_>
subscription.rs:300	lock()	MutexGuard<rcl_subscription_t>	MutexGuard<'_, rcl_subscription_t>
timer.rs:509	handle()	RclPrimitiveHandle	RclPrimitiveHandle<'_>
wait_set/guard_condition.rs:221	handle()	RclPrimitiveHandle	RclPrimitiveHandle<'_>
wait_set/rcl_primitive.rs:30	handle() (trait def)	RclPrimitiveHandle	RclPrimitiveHandle<'_>

Why this matters

• Explicit lifetimes make borrow relationships clearer to readers
• Aligns with modern Rust idioms and style guidelines
• Helps catch bugs during future refactoring
• As a reference implementation for ROS2 Rust development, rclrs should model good practice

Proposed fix

Add explicit '_ lifetime annotations to all affected return types. The fix for the trait definition in wait_set/rcl_primitive.rs will need to be applied consistently across all trait implementations.

Testing

• Verify clean build with no mismatched_lifetime_syntaxes warnings on Humble, Jazzy, and Rolling
• Run existing test suite to confirm no regressions

I'm happy to contribute a PR for this fix. Thanks for your efforts in bringing Rust to ROS2 !

[BrandonSimoncic]

Anything I can do to contribute to this? I'm tired of looking at these warnings too.

[esteve]

@gsokoll thanks for the heads-up, I see you've fixed this issue in gsokoll@5d2025e, would you like to submit a PR so I can review the changes?

@BrandonSimoncic thanks, it'd be great if @gsokoll can submit a PR, I'll ping you if you'd like to have a look it