feat: support and validate query table with multiple-levels path

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There are some problems when users try to query a table named by multiple levels.
For example, given a statement like: `SELECT col1, col2 from db1.t1;`. We are expecting:
- there is a table `t1` under database `db1`
- the current execute-engine is running on database `db1`

Similar rules should be applied on `CREATE INDEX ... `, `CREATE PROCEDURE ... ` and other statements as well

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该 issue 提到在 SELECT、CREATE INDEX 和 CREATE PROCEDURE 语句中查询带有多级路径（如 `db1.t1`）的表。请在 codebase 中查找 SQL parser 和 validation 逻辑，可能在 src/parser 或 src/sql 这样的目录中。需要理解 execution engine 当前如何处理 database context 和 table resolution。解决方案涉及扩展 validation，以在各类 statement types 中支持并强制执行多级路径语法。

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