Restructure Core V2 libraries into /sdk/corev2/

[alzimmermsft]

Description

Replacement for #44434 as it had too many merge conflicts.

Moves the *-v2 libraries under sdk/core to sdk/corev2 to allow for those libraries to re-use the same artifactId but under a different groupId (com.azure:azure-core -> com.azure.v2:azure-core). This updates some engineering scripts to support the new groupId and leaves a few comments on where additional support will be needed in the future.

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• The pull request does not introduce [breaking changes]
• CHANGELOG is updated for new features, bug fixes or other significant changes.
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