Add new chart for swh-loader-metadata

This adds loader-metadata charts.

(This is to be reviewed commit per commit.) The main functionality is in the commit 2 (chart) and 3 (test).

This also adds a Makefile (commit 1) to explicit how to run tests (as already explained in the readme but now it's executable).

Tests are happy [1] and helm install as well [2] (no output as it's real long).

[1]

make test

$ make test
docker run -ti --user 1000 --rm -v /home/tony/work/swh/sysadm-environment/swh-charts:/apps \
  "helmunittest/helm-unittest:3.11.1-0.3.0" swh

Chart [ swh ] swh
PASS  test graphql deployment  swh/tests/graphql_configmap_test.yaml
PASS  test graphql deployment  swh/tests/graphql_deployment_test.yaml
PASS  test graphql deployment  swh/tests/graphql_global_test.yaml
PASS  test graphql deployment  swh/tests/graphql_service_test.yaml
PASS  test loader_metadata configmap deployment        swh/tests/loader_metadata_configmap_test.yaml
PASS  test loader_metadata configmap utils deployment  swh/tests/loader_metadata_configmap_utils_test.yaml
PASS  test loader_metadata deployment  swh/tests/loader_metadata_deployment_test.yaml
PASS  test global loader metadata deployment   swh/tests/loader_metadata_global_test.yaml
PASS  test loader_metadata keda-scaling        swh/tests/loader_metadata_keda_autoscaling_test.yaml
PASS  test loader_metadata keda-secrets        swh/tests/loader_metadata_keda_secrets_test.yaml
PASS  test memcached deployment        swh/tests/memcached_deployment_test.yaml
PASS  test memcached deployment        swh/tests/memcached_global_test.yaml
PASS  test memcached service   swh/tests/memcached_service_test.yaml
PASS  test memcached ServiceMonitor    swh/tests/memcached_servicemonitor_test.yaml
Charts:      1 passed, 1 total
Test Suites: 14 passed, 14 total
Tests:       27 passed, 27 total
Snapshot:    0 passed, 0 total
Time:        102.975784ms

[2] if we agree no the makefile idea, we could add a target 'install-dry-run' (or something) with the following

helm install --values values-swh-application-versions.yaml  --values swh/values/default.yaml --values swh/values/staging.yaml swh-test swh --dry-run --debug --set namespace=test 2>&1 | less

Refs. swh/infra/sysadm-environment#4794 (closed)

/cc @teams/sysadmin