UMF Transformer Enhancements and Optimization

[jeff-yin]

Transformer infrastructure -- memory, CRUD/GET operation optimizations, UT. This is a dependency for UMF Subscription support being contributed by Broadcom. This entry was opened to account for Dell's portion of the contribution toward UMF Subscription; it uses the same parent PR as the "UMF Subscription Infra (#1191)" project.

Code PRs:

Repo	PR title	State
sonic-mgmt-common	Apply goyang patch xfmr memory optimization	Open
	Transformer Infra memory optimization and enhancements	Open
	Transformer Infra Unit Tests	Open

[zhangyanzhao]

@jeff-yin can you please help to add Transformer Infra UT PR to #1287?

[zhangyanzhao]

HLD and code PRs are merged. Close this as done.