add namespace param for fn and env (#2556)

This PR moves fission CLI as closer as possible to kubectl command behaviour.  We have improved namespace handling behaviour across CLI.

* add namespace param for fn and env
* use common fn for ns check
* update validation
* default namespace for httpTrigger, env and package, config and triggers
* use default ns
* add namespace filter to spec
* add forceNamespace flag
* set current namespace
* add default namespace in config
* add namespace specific destroy
* add all namespace in the list of resources
* add namespace as global tag
* use %s instead of %v
* add test cases for namespace
* use ns in get all functions

test/tests/test_namespace/test_ns_current_context.sh

@@ -0,0 +1,39 @@
+#!/bin/bash
+
+set -euo pipefail
+source $(dirname $0)/../../utils.sh
+
+TEST_ID=$(generate_test_id)
+echo "TEST_ID = $TEST_ID"
+
+tmp_dir="/tmp/test-$TEST_ID"
+mkdir -p $tmp_dir
+
+ROOT=$(dirname $0)/../../..
+
+cleanup() {
+    echo "previous response" $?
+    log "Cleaning up..."
+    clean_resource_by_id $TEST_ID
+    rm -rf $tmp_dir
+}
+
+if [ -z "${TEST_NOCLEANUP:-}" ]; then
+    trap cleanup EXIT
+else
+    log "TEST_NOCLEANUP is set; not cleaning up test artifacts afterwards."
+fi
+
+httptrigger=http-$TEST_ID
+httptriggerurl=/url-$TEST_ID
+fn_n=nbuilderhello-$TEST_ID
+
+cd $ROOT/examples/go/hello-world
+
+log "Creating httptrigger using default namespace"
+fission  httptrigger create --function $fn_n --url /$httptriggerurl --name $httptrigger
+
+log "verify trigger exists"
+fission httptrigger list --namespace default | grep $httptrigger
+
+log "Test PASSED"