[Public] Add APIMappingUtilTest

[dulithsenanayake]

This PR adds APIMappingUtilTest

[CLAassistant]

All committers have signed the CLA.

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 47.16%. Comparing base (09742ad) to head (5600d1c). Report is 13 commits behind head on master.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #12388 +/- ## ============================================= + Coverage 20.02% 47.16% +27.14% - Complexity 0 4210 +4210 ============================================= Files 1235 1869 +634 Lines 106163 138154 +31991 Branches 14897 19984 +5087 ============================================= + Hits 21255 65160 +43905 + Misses 82106 65258 -16848 - Partials 2802 7736 +4934 ``` | [Flag](https://app.codecov.io/gh/wso2/carbon-apimgt/pull/12388/flags?src=pr&el=flags&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=wso2) | Coverage Δ | | |---|---|---| | [integration_tests](https://app.codecov.io/gh/wso2/carbon-apimgt/pull/12388/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=wso2) | `41.74% <ø> (?)` | | | [unit_tests](https://app.codecov.io/gh/wso2/carbon-apimgt/pull/12388/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=wso2) | `20.12% <ø> (+0.10%)` | :arrow_up: | Flags with carried forward coverage won't be shown. [Click here](https://docs.codecov.io/docs/carryforward-flags?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=wso2#carryforward-flags-in-the-pull-request-comment) to find out more.

:umbrella: View full report in Codecov by Sentry.
:loudspeaker: Have feedback on the report? Share it here.