test: add test case for metric_store and metric_view

[xuan-cao-swi]

Closes #1890

Description

Found a couple of issues while developing the test case:

1. The current callback timeout applies to the entire set of callbacks of the instrument instead of each callback individually. This PR fixes that.
2. A faulty callback that raises an error can crash the entire application. This update adds a safeguard to log the error while allowing the application to continue running. Also we shouldn't update to instrument and merge attributes if callback return non-numeric data or nil. (Reference)
3. Replace Timeout.timeout with thread for executing the callback.
4. Currently, each instrument supports only one view. Assigning multiple views to the same instrument can lead to inconsistent data_point values, as each view may modify the underlying data. This PR does not address the issue, but it will be resolved in the future.

Each metric_stream should be bound to its own instrument. While most functionality is tested through instruments, here we focus on fundamental correctness, which will be important when views and exemplars are updated.