[maps] Azure Maps Track2 data-plane onboarding

[ambientlight]

• The purpose of this PR is explained in this or a referenced issue.
• The PR does not update generated files.
• Tests are included and/or updated for code changes: full set of samples at [Track2] Azure Maps Samples Azure-Samples/azure-sdk-for-go-samples#298
• Updates to CHANGELOG.md are included.
• MIT license headers are included in each file.

Initial onboarding of Azure Maps data-plane client libraries (9 clients) following Azure/azure-rest-api-specs#14871

SDK track2 autogen by https://github.com/ambientlight/azure-rest-api-specs/blob/experiment-scripts/gen_go.sh

This PR patches generated files

1. To alleviate Custom marshalling/unmarshalling is broken for types composed of multiple types autorest.go#652, json Marshall/Unmarshall has been manually fixed all types containing multiple embedded structs at a9720a7 and ada90e7
2. x-ms-long-running-operations extension does not support custom headers, while Azure Maps AD Authentication requires additional x-ms-client-id header in addition to OAuth2 Bearer auth token, and so additional policy that adds this header to all requests has been injected into all clients via cd951cf and 049a823
3. OpenAPI 2.0 spec does not support polymorphic parameter types in definition and thus won't go well with generated json parsing, so when json properties of different types are returned, unmarshall will fail, and so type definitions where polymorphic types are occurring has been relaxed to interface{} via 981c73c, 71dd086, 23553ae
4. Incorrect swagger property definition type(WindDirection) has been fixed to reflect [Maps] [Hub Generated] fix WindDirection incorrect degrees type: int32 -> float in Maps Weather preview/1.0 azure-rest-api-specs#15361 via 30f82eb
5. VSCode golang plugin also fixed some indentation issues of generated code.

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[ghost]

Hi @ambientlight. Thank you for your interest in helping to improve the Azure SDK experience and for your contribution. We've noticed that there hasn't been recent engagement on this pull request. If this is still an active work stream, please let us know by pushing some changes or leaving a comment. Otherwise, we'll close this out in 7 days.

[ghost]

Hi @ambientlight. Thank you for your contribution. Since there hasn't been recent engagement, we're going to close this out. Feel free to respond with a comment containing "/reopen" if you'd like to continue working on these changes. Please be sure to use the command to reopen or remove the "no-recent-activity" label; otherwise, this is likely to be closed again with the next cleanup pass.