KIP-340 — Allow kafka-reassign-partitions.sh and kafka-log-dirs.sh to take admin client property file

Discussion Kafka 2.1 Admin

Adds a `--command-config` argument to both `kafka-reassign-partitions.sh` and `kafka-log-dirs.sh` so that arbitrary `AdminClient` properties (SSL, SASL, etc.) can be supplied via a properties file. Both tools hardcode `AdminClient` construction with only `bootstrap.servers`, making them unusable against TLS-secured clusters.

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