[action] [PR:471] [xcvrd] Modify to support regular expression when parsing the key in media_settings.json (#471)

[mssonicbld]

• [xcvrd] Modify to support regular expression when parsing the key in media_settings.json

• fix unit test error

• add unit test for getting media settings value with regular expression

• define get_media_settings()

• apply the suggestion for if condition

[mssonicbld]

Original PR: https://github.com/sonic-net/sonic-platform-daemons/pull/471