[Feature] Configdump: show symcache flags in --symbol-details

[Feature] Configdump: show symcache flags in --symbol-details

Add a `flags` array (fine, empty, explicit_disable, explicit_enable,
ignore_passthrough, nostat, idempotent, mime, trivial, skip, composite,
ghost, coro) to the per-symbol details, so it is possible to check
whether a symbol requires explicit enabling; structural types are
already covered by the `type` field.