[roll] Roll fuchsia [ffx][trace] use concrete error types

Refactor the `trace` host library (`ffx_tracing` crate) to replace generic
`anyhow::Result` with a 100% pure structured type error boundary.

- Added a dedicated `error` module defining `TraceError` and a module-level
  `Result<T>` alias.
- Expanded `TraceError` to encompass low-level binary stream packet decoding
  and string formatting failure paths: `Format`, `UnknownMethodOrdinal`, and
  `AmbiguousDecoding`.
- Purged all raw `anyhow` macro hooks (`anyhow!`, `bail!`) from public and
  private logic structures alike inside `lib.rs` and `fidl.rs`.
- Extracted the `"//third_party/rust_crates:anyhow"` dependency entry from the
  crate's `BUILD.gn` entirely.
- Adapted the downstream `plugins/trace` consumer to explicitly capture and
  box the refined `Result<T, TraceError>` into anyhow at its execution boundary.

Test: `fx test ffx_tracing_lib_test` and `fx test ffx_trace_lib_test`
Original-Original-Reviewed-on: https://fuchsia-review.googlesource.com/c/fuchsia/+/1598870
Original-Original-Revision: 2823d8b365a4063c835db847056123556999cce1
GitOrigin-RevId: 9fe095c650f1e65019cb6a41334bf6a71df5b5c5
Change-Id: I7b53cca4d0c16777e5babbb850790c10172bbd20
Reviewed-on: https://fuchsia-review.googlesource.com/c/integration/+/1613125
Cr-Commit-Position: refs/heads/main@{#192760}