feat(coredhcp/coresmd): implement flexible hostname policy

[synackd]

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Description

Replace the hostname_by_type, hostname_default, *_pattern, etc. hostname specifiers with a flexible, rich hostname rule system specified by one or more hostname_rule specifiers. hostname_rule allows arbitrary matching apecifiers (e.g. type for SMD component type, subnet) to be specified to apply hostname patterns for. The specification of multiple rules behaves like iptables/nftables chains in the way that a given components traverse the rule list until a rule matches or the list is exhausted.

node_pattern and bmc_pattern will still work, though they will be converted into hostname rules if used, which means that the order they are specified will potentially matter.

See examples/coredhcp/hostnames.md for more documentation on how rules work.

Fixes #46

NOTE: For testing, a replace directive in go.mod is necessary to use the local repository's packages:

go mod edit -replace=github.com/openchami/coresmd=./

Type of Change

• Bug fix
• New feature
• Breaking change
• Documentation update

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