Migrate Transaction to pro-macros

[ItoroD]

Description

This PR migrates Transaction to pro-macros

Notes to the reviewers

• Policy link is broken in fn vsize(&self) see main doc [here ]. So I took that part out of the doc here (https://docs.rs/bitcoin/latest/bitcoin/struct.Transaction.html#method.vsize)
• I am not sure if this is the right api docs for serialize(&self) here
• I wondering if we need to put a doc for the default constructor.

Checklists

All Submissions:

• [x] I've signed all my commits
• [x] I followed the contribution guidelines
• [x] I ran cargo fmt and cargo clippy before committing

New Features:

• [x] I've added docs for the new feature