This constructor will simplify upcoming commits by performing all of the
necessary initialization for the FakeIdentityAllocator in all tests that
make use of this structure.

Signed-off-by: Joe Stringer <joe@cilium.io>

Upcoming commits will rely on the daemon passing the identityAllocator
module down to the fqdn subsystem via the policy repository. For now,
adjust the function signatures to pass this through, but avoid actually
using the new parameter for now.

This commit is a functional no-op but reduces the noise in terms of code
churn from upcoming commits.

Signed-off-by: Joe Stringer <joe@cilium.io>

In order to test an upcoming bugfix, the internal FQDN handling
functions that are triggered from the unit tests must be able to refer
to an abstract identity allocator. This will then be mocked out by the
tests.

This commit extends the existing cache.IdentityAllocator interface to
support allocating identities for CIDRs. A future commit will also add
Identity release functions to the same abstraction.

This also paves the way for some improvements to code structure: Some of
the FQDN logic under `daemon/cmd/fqdn.go` may be able to be pushed down
into pkg/fqdn now that it doesn't directly reference the globals from
the ipcache package.

There's another remaining open question around code structure for how
the IPcache and identity allocation packages handle the pattern for
allocating CIDR identities vs. injecting those identities into the
underlying IPcache maps (eg in eBPF). This commit shies away from
solving that problem right now in order to keep the changes minimal as
this code is likely to be proposed for backport.

Signed-off-by: Joe Stringer <joe@cilium.io>

An upcoming commit will introduce a new variation on the release
function, so just rename this one here to simplify the upcoming changes.

Signed-off-by: Joe Stringer <joe@cilium.io>

Everything that goes up must eventually come down. And so it is also
with everything that is allocated; it must be deallocated.

Extend the IdentityAllocator interface to also support CIDR release
functions and plumb through an initial implementation. This is currently
not hooked into the agent itself, this will come with an upcoming bugfix
instead.

Signed-off-by: Joe Stringer <joe@cilium.io>