OA crash handling to reinitialize port through xcvrd (sonic-net#1432)

* OA crash handling to reinitialize port through xcvrd

* Added table to list values for MEDIA_SETTINGS_SYNC_STATUS

* Fixed typo

* Addressed PR comment

* Addressed PR comments and separated media notification between SfpStateUpdateTask and CmisManagerTask threads

* Modified media settings to NPU SI settings for clearly differentiating module v/s NPU SI settings in future

* Fixed typo

* Addressed PR comments

* Reverted unrelated changeset

* Addressed PR comments

* Added pre-requisite section and added testcase for OA restart

* Corrected typo in XCVRD init sequence diagram

* Added description and functioning related to is_npu_si_settings_update_required

* Fixed typo

* Addressed review comments

* Replaced usage of PORT_TABLE for storing the keys from APPL_DB to STATE_DB