feat: add jsd loss and asymmetric loss

[wcrzlh]

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• [x] You have read the Contributing Guidelines on pull requests
• [x] Your code builds clean without any errors or warnings
• [x] You are using approved terminology
• [x] You have added unit tests

Motivation

Jsd loss and asymmetric loss are added.

Test Plan

(How should this PR be tested? Do you require special setup to run the test or repro the fixed bug?)

Related Issues and PRs

Related issue: https://github.com/mindspore-lab/mindcv/issues/621

[geniuspatrick]

please add some unit tests

[wcrzlh]

added