feat(chart): add resourcesPreset support (Bitnami-style resource tiers)

[danielqb]

Resources for php-fpm, nginx, mariadb, and redis were only configurable
as full explicit request/limit blocks. Bitnami charts offer a lighter-weight
alternative via a resourcesPreset value (none/nano/micro/small/medium/
large/xlarge/2xlarge) that maps to a predefined table, useful for quick
sizing without hand-writing CPU/memory numbers.

• Added glpi.resources.preset helper in _helpers.tpl with the same
  tiers/values as bitnami/common's common.resources.preset, so operators
  already familiar with that convention get predictable numbers here.

• Added glpi.resources helper: renders the explicit resources dict if
  non-empty, otherwise falls back to resourcesPreset (renders nothing
  if both are unset/none).

• Added resourcesPreset: "none" alongside the existing resources blocks
  for glpi.phpfpm, glpi.nginx, mariadb.primary, and redis in values.yaml.
  Existing concrete resources values are UNCHANGED and still take
  precedence by default - this is purely additive, zero behavior change
  unless a user explicitly clears resources to use a preset instead.

• Updated glpi-deployment.yaml (php-fpm + nginx), mariadb-statefulset.yaml,
  and redis-deployment.yaml to use the new helper.

• helm lint: 0 failures

• helm template (default): resources unchanged (1000m/512Mi php-fpm,
  500m/256Mi nginx, matches pre-existing values)

• helm template --set glpi.phpfpm.resources=null --set
  glpi.phpfpm.resourcesPreset=large: renders 1.5cpu/3072Mi limits,
  1.0cpu/2048Mi requests (matches Bitnami's "large" tier)

• helm template --set redis.resources=null (resourcesPreset stays
  "none" default): no resources block rendered at all

[eduardofraga]

Move files from kubernetes/glpi/ to helm/