Improving support for `CREATE PROCEDURE`

sqlparser-rs currently doesn't have great support for `CREATE PROCEDURE` statements, leading to parser errors when I pass in valid SQL. I'd like to work on improving this (I've already started on [my fork](https://github.com/ZacJW/sqlparser-rs/tree/dev)).

What's the project's ideal vision for how this would be handled? Stored procedures are the kind of thing that can be very RDBMS specific. Do you just want the AST to cover what's in the standard, but the dialects to accept but discard additional options?

The first fix which will be ready to go once I've written tests is #1901, support for what PostgreSQL calls argmode and the standard calls parameter mode.

## PRs

- #1901
- #1903

首先检查作者 fork 的 dev 分支中的现有工作，以及链接的 issue 和 PR #1901、#1903。明确项目对 CREATE PROCEDURE 的 AST 和方言行为的预期，然后添加覆盖已达成共识的支持的测试，使有效的 SQL 能按预期完成解析。

由索引模型根据 Issue 内容生成。