Fix AST documentation formatting and remove pointless comments

[Copilot]

This PR addresses two specific documentation issues in the oxc_ast crate as outlined in the issue:

Fixed Issue #5: Inconsistent formatting

Problem: Type names and references were inconsistently formatted in doc comments.

Solution: Standardized all type references to use proper Rust doc formatting:

• Fixed markdown-style links: [variable declarations](VariableDeclaration) → [VariableDeclaration]
• Added backticks to unformatted type names: Empty Statement → EmptyStatement
• Standardized 20+ statement and expression type comments for consistency

Examples of changes:

// Before
/// A single variable declaration in a list of [variable declarations](VariableDeclaration).
/// Empty Statement
/// Catch Clause in a [`try/catch` statement](TryStatement).

// After  
/// A single variable declaration in a list of variable declarations ([`VariableDeclaration`]).
/// `EmptyStatement`
/// Catch Clause in a [`TryStatement`].

Fixed Issue #4: Pointless comments

Problem: Many doc comments contained redundant text that just repeated what the struct fields already showed.

Solution: Removed "includes..." patterns that added no value beyond the type definition itself:

// Before
/// `foo = 1` in `let foo; foo = 1;`
///
/// Represents an assignment expression, which includes an operator, a target, and an expression.

// After
/// `foo = 1` in `let foo; foo = 1;`

Removed patterns:

• "which includes an operator and an argument"
• "which includes a left expression, an operator, and a right expression"
• "which includes a test, a consequent, and an alternate"
• "which includes an operator, a target, and an expression"
• "which includes a binding, and an optional init expression"
• "which includes a name and a binding"

All meaningful documentation (examples, syntax explanations, links to specs) was preserved. Only redundant field descriptions were removed.

Impact: 11 lines of pointless documentation removed, 27 lines improved for consistency. Documentation is now cleaner and more useful while maintaining all essential information.

Fixes #12728.

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