Support auto direction

[msune]

Add a new DIRECTION supported value, auto, and set it as default.

As opposed to ingress, egress and both, which attach ALL rules to the specified direction(s), auto would split and load funneling rules to EGRESS and unfunneling rules INGRESS, effectively being equivalent to two runs of sfunnel with the corresponding subset of rules.

This would allow turning this:

--- a/nginx.yaml
+++ b/nginx.yaml
@@ -1,21 +1,31 @@
 apiVersion: apps/v1
 kind: Deployment
 metadata:
   name: my-nginx-deployment
 spec:
   replicas: 4
   selector:
     matchLabels:
       app: my-nginx-app
   template:
     metadata:
       labels:
         app: my-nginx-app
     spec:
       containers:
+        - name: sfunnel-init
+          env:
+            - name: SFUNNEL_RULESET
+              value: ip tcp dport 80 sport 540 actions unfunnel tcp
+          image: ghcr.io/datahangar/sfunnel:0.0.11
+          securityContext:
+            privileged: false #Set to true for some public clouds (e.g. GKE standard)
+            capabilities:
+              add: [BPF, NET_ADMIN, SYS_ADMIN]
+          volumeMounts:
+            - name: bpffs
+              mountPath: /sys/fs/bpf
+        - name: sfunnel-init-egress
+          env:
+            - name: SFUNNEL_RULESET
+              value: ip tcp sport 8080 actions funnel tcp dport 540 sport 80
+            - name: DIRECTION
+              value: egress
+          image: ghcr.io/datahangar/sfunnel:0.0.11
+          securityContext:
+            privileged: false #Set to true for some public clouds (e.g. GKE standard)
+            capabilities:
+              add: [BPF, NET_ADMIN, SYS_ADMIN]
+          volumeMounts:
+            - name: bpffs
+              mountPath: /sys/fs/bpf

into this:

--- a/nginx.yaml
+++ b/nginx.yaml
@@ -1,21 +1,31 @@
 apiVersion: apps/v1
 kind: Deployment
 metadata:
   name: my-nginx-deployment
 spec:
   replicas: 4
   selector:
     matchLabels:
       app: my-nginx-app
   template:
     metadata:
       labels:
         app: my-nginx-app
     spec:
       containers:
+        - name: sfunnel-init
+          env:
+            - name: SFUNNEL_RULESET
+              value: ip tcp dport 80 sport 540 actions unfunnel tcp; ip tcp dport 80 sport 540 actions unfunnel tcp
+          image: ghcr.io/datahangar/sfunnel:0.0.11
+          securityContext:
+            privileged: false #Set to true for some public clouds (e.g. GKE standard)
+            capabilities:
+              add: [BPF, NET_ADMIN, SYS_ADMIN]
+          volumeMounts:
+            - name: bpffs
+              mountPath: /sys/fs/bpf

[msune]

This in conjunction with #3 in auto mode would properly cover most of the use-cases.