Activity options merging logic is not correct

Expected Behavior

There are six potential sources for activity options:

1. WorkflowImplementationOptions#defaultActivityOptions
2. WorkflowImplementationOptions#activityOptions map
3. Workflow.setDefaultActivityOptions
4. Workflow.applyActivityOptions map
5. options argument passed to WorkflowInternal#newActivityStub
6. activityMethodOptions map argument passed to WorkflowInternal#newActivityStub

When all these options are specified for the given activity type, the logical behavior is to merge them in the same order as specified above.

Actual Behavior

The current logic is split between:

https://github.com/temporalio/sdk-java/blob/8af4a2647dacab2cb0d4a3a613482e00bc297a39/temporal-sdk/src/main/java/io/temporal/internal/sync/WorkflowInternal.java#L303

and

https://github.com/temporalio/sdk-java/blob/16755a1bb7ebba29fb820b86a001c079cf4ffb62/temporal-sdk/src/main/java/io/temporal/internal/sync/ActivityInvocationHandler.java#L70

The short description is:

1. options = options argument passed to [WorkflowInternal#newActivityStub] ? WorkflowImplementationOptions#defaultActivityOptions // not that they are not merged if the argument is present.

2. WorkflowImplementationOptions#activityOptions map is overridden by options found in activityMethodOptions map argument passed to WorkflowInternal#newActivityStub

3. options (from step 1) are overridden by a value (with the key equal to the activity type) from the map generated by step (2)

I believe that we should fix the merging logic to match the intuitive behavior explained in the "Expected Behavior" section.

Start with the referenced logic in temporal-sdk/src/main/java/io/temporal/internal/sync/WorkflowInternal.java and ActivityInvocationHandler.java, then trace the six activity-option sources listed in the issue. Compare their current precedence with the expected order and verify that the resulting merge preserves each layer’s overrides. Done means the implementation follows the specified order for options supplied to the activity stub.