[roll] Roll fuchsia [ffx][fastboot] migrate library to concrete errors and adapt callers

Refactor the `ffx_fastboot` library to utilize structured errors instead
of generic anyhow bails, improving error definition purity. Adapt target
plugins to handle the new explicit error types.

- src/developer/ffx/lib/fastboot/src/unlock/mod.rs:
  - Excise `ffx_bail!` macros and replace them with explicit returns of
    `FfxFastbootError` variants (`AlreadyUnlocked`, `MissingCredentials`).

- Downstream Plugin Adaptations (bootloader, fastboot, flash plugins):
  - Update `try_join!` invocation graphs in `target/bootloader`,
    `target/fastboot`, and `target/flash` plugins.
  - Append explicit `.map_err(anyhow::Error::from)` to `ffx_fastboot`
    library calls (`info`, `lock`, `unlock`, `boot`, `from_manifest`,
    `flash`) to align error types within the join macros, accommodating
    the library's shift from anyhow results to typed `FfxFastbootError`
    results.

Original-Original-Reviewed-on: https://fuchsia-review.googlesource.com/c/fuchsia/+/1602091
Original-Original-Revision: 3514c91d71d6cec2a8eb9e69be465294672f502c
GitOrigin-RevId: 650962898301ed0ebef7d555a41058f1f92e9d03
Change-Id: Ib66733da99f686621e88cb6d2f3a41c16df02931
Reviewed-on: https://fuchsia-review.googlesource.com/c/integration/+/1613689
Cr-Commit-Position: refs/heads/main@{#192781}