* acl/policy: add PolicyList for global ACLs

* acl/acl: plugin policy

* acl/acl: maxPrivilege is required to allow "list"

* nomad/csi_endpoint: enforce plugin access with PolicyPlugin

* nomad/csi_endpoint: check job ACL swapped params

* nomad/csi_endpoint_test: test alloc filtering

* acl/policy: add namespace csi-register-plugin

* nomad/job_endpoint: check csi-register-plugin ACL on registration

* nomad/job_endpoint_test: add plugin job cases

* acl/policy: add the volume ACL policies

* nomad/csi_endpoint: enforce ACLs for volume access

* nomad/search_endpoint_oss: volume acls

* acl/acl: add plugin read as a global policy

* acl/policy: add PluginPolicy global cap type

* nomad/csi_endpoint: check the global plugin ACL policy

* nomad/mock/acl: PluginPolicy

* nomad/csi_endpoint: fix list rebase

* nomad/core_sched_test: new test since #7358

* nomad/csi_endpoint_test: use correct permissions for list

* nomad/csi_endpoint: allowCSIMount keeps ACL checks together

* nomad/job_endpoint: check mount permission for jobs

* nomad/job_endpoint_test: need plugin read, too

Fix a bug where a millicious user can access or manipulate an alloc in a
namespace they don't have access to.  The allocation endpoints perform
ACL checks against the request namespace, not the allocation namespace,
and performs the allocation lookup independently from namespaces.

Here, we check that the requested can access the alloc namespace
regardless of the declared request namespace.

Ideally, we'd enforce that the declared request namespace matches
the actual allocation namespace.  Unfortunately, we haven't documented
alloc endpoints as namespaced functions; we suspect starting to enforce
this will be very disruptive and inappropriate for a nomad point
release.  As such, we maintain current behavior that doesn't require
passing the proper namespace in request.  A future major release may
start enforcing checking declared namespace.

This adds an initial implementation of ACLs for HostVolumes.

Because HostVolumes are a cluster-wide resource, they cannot be tied to
a namespace, thus here we allow similar wildcard definitions based on
their names, tied to a set of capabilities.

Initially, the only available capabilities are deny, or mount. These
may be extended in the future to allow read-fs, mount-readonly and
similar capabilities.

This commit adds basic support for globbing namespaces in acl
definitions.

For concrete definitions, we merge all of the defined policies at load time, and
perform a simple lookup later on. If an exact match of a concrete
definition is found, we do not attempt to resolve globs.

For glob definitions, we merge definitions of exact replicas of a glob.

When loading a policy for a glob defintion, we choose the glob that has
the closest match to the namespace we are resolving for. We define the
closest match as the one with the _smallest character difference_
between the glob and the namespace we are matching.