feat: Support concurrent executing at fragments level

[Xuanwo]

This PR will support concurrent executing at fragments level, remove the global mutex.

This PR also adds the filter pushdown support:

query I
SELECT count(*) FROM 'test/test_data.lance' WHERE age > 30
----
3

query I
SELECT count(*) FROM 'test/test_data.lance' WHERE name IN ('Alice', 'Eve')
----
2

query I
SELECT count(*) FROM 'test/test_data.lance' WHERE age > 30 AND score < 90
----
2

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Parts of this PR were drafted with assistance from Codex (with gpt-5.2) and fully reviewed and edited by me. I take full responsibility for all changes.