feat(analysis/normed_space/star/gelfand_duality): Show the Gelfand transform is a bijective isometry for C⋆-algebras over ℂ (#16488)
- [x] depends on: #16451
- [x] depends on: #16438
- [x] depends on: #16368
- [x] depends on: #16303
- [x] depends on: #16446
- [x] depends on: #16448