Fix RC1 issues

[popduke]

1. correct License/Notice files & add missing license headers
2. improve verification / test experience and refine test steps in readme
3. fixed path issue in generated .sha512 files

[coveralls]

Pull Request Test Coverage Report for Build 20295608872

Details

• 0 of 0 changed or added relevant lines in 0 files are covered.
• 81 unchanged lines in 10 files lost coverage.
• Overall coverage increased (+0.001%) to 65.134%

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Files with Coverage Reduction	New Missed Lines	%
org/apache/bifromq/basecluster/memberlist/AutoHealer.java	1	95.51%
org/apache/bifromq/basecluster/memberlist/AutoSeeder.java	1	80.49%
org/apache/bifromq/basecrdt/store/AntiEntropy.java	1	82.69%
org/apache/bifromq/basekv/raft/RaftNodeStateLeader.java	1	86.18%
org/apache/bifromq/basekv/raft/RaftNodeStateFollower.java	4	83.86%
org/apache/bifromq/inbox/store/InboxStoreCleaner.java	4	85.05%
org/apache/bifromq/inbox/store/InboxStoreCoProc.java	7	79.14%
org/apache/bifromq/dist/trie/TopicFilterIterator.java	9	71.06%
org/apache/bifromq/inbox/server/TenantGCRunner.java	9	5.63%
org/apache/bifromq/basekv/localengine/rocksdb/RocksDBKVSpaceEpochHandle.java	44	43.72%

Totals
Change from base Build 20027949465:	0.001%
Covered Lines:	27856
Relevant Lines:	41280

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💛 - Coveralls