SNOW-1486596: Add support for --stdin for SPCS spec path

[kameshsampath]

Description

As a developer creating SPCS service, I would like to pass the spec YAML using heredoc. Since other commands e.g. snow sql supporting SQL it will be consistent and nice to have the same with SPCS and other commands where we pass file parameter.

e.g.

cat <<EOF |
snow spcs service create foo  --family --spec-stdin
spec:
  containers:
    - name: nginx
      image: /CHEATSHEETS_DB/DATA_SCHEMA/my_image_repository/nginx
      readinessProbe:
        port: 80
        path: /
  endpoints:
    - name: nginx
      port: 80
      public: true
EOF

Context

SPCS service create