implement Extend<{Group, Literal, Punct, Ident}> for TokenStream

[Qelxiros]

Tracking issue: #112815

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[dtolnay]

@rust-lang/libs-api:
@rfcbot fcp merge

These impls enable the following simplification in macro code written without quasi-quoting (#54722):

  let mut stream = TokenStream::new();
- stream.extend([TokenTree::Literal(Literal::i32_suffixed(0))]);
+ stream.extend([Literal::i32_suffixed(0)]);

[rfcbot]

Team member @dtolnay has proposed to merge this. The next step is review by the rest of the tagged team members:

• @Amanieu
• @BurntSushi
• @dtolnay
• @joshtriplett
• @m-ou-se
• @the8472

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