[Docs cleanup] Remove AutoRest SDK config (readme.*.md) and legacy sample files

**Context:** Per-language AutoRest `readme.*.md` config and hand-written sample specs are legacy now that
SDKs are generated from TypeSpec emitters via the spec-gen-sdk pipeline. Several of these files are already
labeled "obsolete". This issue tracks deleting/archiving them.

> ⚠️ Need to decide whether we remove them completely or add an archive notice.
And for sample files, shall we create an replacement by using TypeSpec?

**Tasks:**

- [ ] 🔴 `documentation/code-gen/configure-cli.md` — archive; replace with TypeSpec emitter + spec-gen-sdk guidance
- [ ] 🔴 `documentation/code-gen/configure-go-sdk.md` — archive; replace with TypeSpec emitter + spec-gen-sdk guidance
- [ ] 🔴 `documentation/code-gen/configure-python-sdk.md` — archive; replace with TypeSpec emitter + spec-gen-sdk guidance
- [ ] 🔴 `documentation/code-gen/configure-typescript-sdk.md` — archive; replace with TypeSpec emitter + spec-gen-sdk guidance
- [ ] 🔴 `documentation/samplefiles/` (entire tree: `README.md`, `ABOUT.md`, `readme.{csharp,go,java,python,typescript}.md`, all sample `.json`) — delete/archive
- [ ] 🔴 `documentation/samplefiles-dp/` (entire tree: `ABOUT.md`, single/multi-client `README.md`, all sample `.json`) — delete/archive