Generate conf.jar from the build and move persistence.xml to eclipselink project

[aihuaxu]

Description

Generate the conf.jar for testing from the build rather than packaging the jar. Also moved persistence.xml to eclipselink subproject.

Fixes #108

Type of change

Please delete options that are not relevant.

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• This change requires a documentation update

How Has This Been Tested?

Please describe the tests that you ran to verify your changes. Provide instructions so we can reproduce. Please also list any relevant details for your test configuration

• Test with existing PolarisEclipseLinkMetaStoreTest
• Test B

Test Configuration:

• Firmware version:
• Hardware:
• Toolchain:
• SDK:

Checklist:

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• I have performed a self-review of my code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes
• Any dependent changes have been merged and published in downstream modules
• If adding new functionality, I have discussed my implementation with the community using the linked GitHub issue
• I have signed and submitted the ICLA and if needed, the CCLA. See Contributing for details.

[snazy]

LGTM!
Thanks for tackling this so quickly!

[snazy]

Tip (not a change request) to avoid string-typo-errors in such cases:

val archiveConf by tasks.registering(Jar::class) {
...
}

tasks.named("test") { dependsOn(archiveConf) }