docs(assembly): add v3.2.3 third-party notice draft

[dillon-zheng]

What problem does this PR solve?

Issue Number: ref #2831

The TiSpark v3.2.3 Spark 3.0 assembly has no release-scoped third-party notice in its packaged JAR. This PR adds an evidence-based draft notice for repository-owner and compliance review.

What is changed and how it works?

• Add assembly/src/main/assembly/ThirdPartyNotices.txt.
  • Scope: the published v3.2.3 Spark 3.0 assembly baseline, SHA-256 116a2ac7909cbe6cbab038f7219d299a6fcefe60ae8120de748ed07aae9eba64.
  • The draft inventories 92 evidenced payload components and retains collected upstream/assembly legal material.
  • It deliberately remains marked DRAFT and NOT APPROVED FOR RELEASE.
• Add it to the assembly descriptor so the built JAR contains ThirdPartyNotices.txt at its root.

Review required before removing the draft marker or using this notice in a release:

• Confirm the proposed SPDX expressions, including dual-license choices for JNA, JAXB API, and checker-compat-qual.
• Confirm ownership/retention decisions for 16 final legal assets and 29 native assets, including Netty tcnative/BoringSSL material.
• Confirm whether org.tikv:tikv-client-java is handled as a third-party component or under a first-party policy.

Check List

Tests

• Manual test: mvn -pl assembly -DskipTests -DskipCloneProtoFiles=true package
  • Build succeeds.
  • ThirdPartyNotices.txt is present at the root of assembly/target/tispark-assembly-3.0_2.12-3.2.3.jar.
  • Its SHA-256 in the built JAR matches the source file: d9445b79854c451fc96ecd32361bfc1d324dfab0fd9d62066399733198cc0509.
• git diff --check

Code changes

• Has exported function/method change
• Has exported variable/fields change
• Has interface methods change
• Has persistent data change

Side effects

• Possible performance regression
• Increased code complexity
• Breaking backward compatibility

Related changes

• Need to cherry-pick to the release branch
• Need to update the documentation
• Need to update the tidb-ansible repository
• Need to be included in the release note

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[pingcap-cla-assistant]

All committers have signed the CLA.

[dillon-zheng]

/type development

[dillon-zheng]

/type enhancement

[dillon-zheng]

/type type/enhancement

[dillon-zheng]

/retest

[dillon-zheng]

/retest