BP-69: Convert bookkeeper-common to slog (phase 1)

[merlimat]

First phase of the slog migration BP-69.
Tracking issue: #4750.

This PR adds the slog dependency and @CustomLog wiring, and converts the bookkeeper-common module. Subsequent PRs will convert the rest of the codebase module by module (stats + allocator, bookkeeper-server, bookkeeper-http + tools, stream/distributedlog, peripheral modules, and a final cleanup).

Summary

• Add io.github.merlimat.slog:slog:0.9.7 to pom.xml (alongside the existing SLF4J API — SLF4J stays on the classpath as the rendering backend; no log-config change required to upgrade).
• Add lombok.config at the repo root so @CustomLog generates a slog Logger instead of an SLF4J one:

  lombok.log.custom.declaration = io.github.merlimat.slog.Logger \
      io.github.merlimat.slog.Logger.get(TYPE)
  

• Convert 6 files in bookkeeper-common:
  • AbstractLifecycleComponent, AutoCloseableLifecycleComponent
  • LogExceptionRunnable, OrderedExecutor, SafeRunnable
  • TestOrderedExecutorDecorators (test class)

Conventions (to be applied throughout the migration)

• @Slf4j → @CustomLog; LoggerFactory.getLogger(X.class) → Logger.get(X.class); naming: static = LOG, instance-bound = log.
• log.info("text {} {}", a, b) becomes log.info().attr("a", a).attr("b", b).log("text") — SLF4J {} params turn into named structured attrs, not printf-style format specifiers.
• Classes with identity (ledgerId, bookieId, …) will (in later PRs) build instance-bound loggers in the constructor so every event carries the identity attributes without repeating them at each call site.
• if (log.isDebugEnabled()) guards are removed; slog returns a no-op Event when the level is disabled.
• Expensive attr values use slog's lambda form (log.debug(e -> ...) or .attr(k, () -> expensive)) so the work is only performed when the level is actually enabled.

Not included in this PR

• No module outside bookkeeper-common is converted.
• No wire-protocol, binary-format, metadata-format, metric, or CLI change.
• Client API changes (withLoggerContext(Map<String, Object>) on CreateBuilder/OpenBuilder/DeleteBuilder) are deferred to a later PR in the BP-69 series.

Test plan

• mvn -pl bookkeeper-common -am compile -DskipTests passes
• Existing bookkeeper-common unit tests still pass
• Rendered log output on a local run unchanged (slog's SLF4J handler forwards structured attrs as MDC, so existing Logback/Log4j2 configs keep working)