Update all node icons to SVG

When listing icons provided by a module, if there is a png and svg
with the same name, only the svg will be listed.

If a node asks for a png icon which is not known, but there is a
corresponding svg, that will be used instead.

packages/node_modules/@node-red/editor-client/src/images/icons/arrow-in.svg

@@ -0,0 +1 @@
+<svg width="40" height="60" xmlns="http://www.w3.org/2000/svg"><path d="M18 5v12H7v26h11v12l14-25z" fill="#fff"/></svg>

packages/node_modules/@node-red/editor-client/src/images/subflow_tab.svg

@@ -0,0 +1 @@
+<svg width="40" height="40" xmlns="http://www.w3.org/2000/svg"><path d="M25 16h7c.58 0 1-.42 1-1v-2c0-.58-.42-1-1-1h-7c-.58 0-1 .42-1 1v2c0 .58.42 1 1 1zM8 28h7c.58 0 1-.42 1-1v-2c0-.58-.42-1-1-1H8c-.58 0-1 .42-1 1v2c0 .58.42 1 1 1zm-.416 11C5.624 39 4 37.375 4 35.416V4.582C4 2.622 5.625 1 7.584 1h24.832C34.376 1 36 2.623 36 4.582v30.834C36 37.376 34.375 39 32.416 39zM32 27H19c0 2.19-1.81 4-4 4H7v4.416c0 .35.235.584.584.584h24.832c.35 0 .584-.235.584-.584v-8.417zm1-2v-6h-8c-2.19 0-4-1.81-4-4h-1c-4.333-.002-8.667.004-13 0v6h8c2.19 0 4 1.81 4 4h13zm0-16V4.582c0-.35-.235-.582-.584-.582H7.584C7.234 4 7 4.233 7 4.582v8.417c4.333.002 8.667.001 13 .001h1c0-2.19 1.81-4 4-4z" color="#000" fill="#333"/></svg>