feat(build/testing): add authz specific integration tests

[GeorgeMac]

This PRs does a few things, but primarily it adds ITs for Authz.

In addition, there were a couple features I snuck in to make it all possible:

1. The ability to add metadata to static tokens though the API
2. The ability to add metadata to the bootstrap token through config
3. All JWT claims prefixed with io.flipt.auth are copied into authentication metadata

Update:

The addition of more cases demonstrated a couple bugs, which this PR address:

1. DeleteNamespace was reporting itself as flag resource type. Meaning you could delete a namespace with flag delete perms.
2. We were not normalizing empty string for namespace to default namespace when creating requests. Meaning you would have to explicitly say I can do X in namespace "" and "default". I changed this so that it normalizes as expected.

Outstanding:

• Cases around mutating actions (create, update, delete)
• Cases specifically for JWT
• Cases specifically for k8s
• Add IT to GH workflow matrix

[markphelps]

looks great to me! thank you for doing all this! has already proven it was necessary

[markphelps]

Suggested change

	t.Run(fmt.Sprintf("InNamespace(%q)", namespace.Key), func(t *testing.T) {
	t.Run(fmt.Sprintf("InNamespace(%q)", namespace.Expected), func(t *testing.T) {

Will prevent "" from showing in output

[GeorgeMac]

This is to test both default and "" (blank) explicitly.
Otherwise, those two test suites will be duplicately named.

[markphelps]

💯

[markphelps]

😲