Implement provisioner

[pleshakov]

Proposed changes

Problem:
Support provisioning NGINX data plane per Gateway, as expected by the Gateway API conformance tests.
See #634 for more info

Solution:

• Implement provisioner command which which provisions a Deployment of NKG (static mode) for each Gateway of the provisioner GatewayClass.
• Add provisioner manifests and docs

Fixes #634

Additionally, introduce PrepareTimeForFakeClient helper function, which
fixes an error that appeared on GitHub Action pipeline, not locally (see below).
(To reproduce it locally, run make TZ=123 unit-tests from an earlier commit
and ensure you
compare Conditions in the status as in
Expect(clusterGc.Status.Conditions).To(Equal(expectedConditions)) )

The timezone of the time in a resource field returned by the fake client was different
from the one set in the field when updating the resource.

The commit adds PrepareTimeForFakeClient() which ensures that the time is prepared
correctly so that the timezone is the same.

The problem is only present when comparing status Conditions using gomega like

Expect(clusterGc.Status.Conditions).To(Equal(expectedConditions))

but not present if comparing using cmp like

Expect(helpers.Diff(expectedGc, latestGc)).To(BeEmpty()).

  [FAILED] Expected
      <*time.Location | 0x30d0b00>: {
          name: "Local",
          zone: [
              {name: "UTC", offset: 0, isDST: false},
          ],
          tx: [
              {
                  when: -9223372036854775808,
                  index: 0,
                  isstd: false,
                  isutc: false,
              },
          ],
          extend: "UTC0",
          cacheStart: -9223372036854775808,
          cacheEnd: 9223372036854775807,
          cacheZone: {name: "UTC", offset: 0, isDST: false},
      }
  to equal
      <*time.Location | 0x309f240>: {name: "UTC", zone: nil, tx: nil, extend: "", cacheStart: 0, cacheEnd: 0, cacheZone: nil}

Checklist

Before creating a PR, run through this checklist and mark each as complete.

• I have read the CONTRIBUTING doc
• I have added tests that prove my fix is effective or that my feature works
• I have checked that all unit tests pass after adding my changes
• I have updated necessary documentation
• I have rebased my branch onto main
• I will ensure my PR is targeting the main branch and pulling from my branch from my own fork