RSDK-5109 - add close function

[purplenicole730]

Jira ticket

Add a close() function to the Python SDK so that users can specify what happens when a resource closes. This function is not meant to be called directly, but rather to be called when a module or resource manager is removing a resource.

Changes

• Added a default close function in ResourceBase that returns nothing, but can be overwritten
• Modules also now call close() when removing a resource
• Unittests added to assert that both default (summation) and overwritten (gizmo) close() functions were called appropriately
• Resource manager now has a close() function, where it calls all its resources' close() functions
• Unittests added to assert that resources' closed functions were called when resource manager's close function called
• Added close functions to most of the examples with a comment explaining that it was completely optional

Closing the resource manager was also tested manually by printing out statements in the example's server.py

[cheukt]

looks pretty good! can you update the docs/example modules to refer to this new functionality as well? In the example modules, I think just logging something will be good, just want to surface the function within the examples

[njooma]

Looks good pending updates from @cheukt's comments

[cheukt]

a few smaller nits

[cheukt]

LGTM