Allow to use 'upgrade' to create an orbital

[alkurbatov]

Currently the only way to morph an orbital command is to:

const { MORPH_ORBITALCOMMAND } = require('@node-sc2/core/constants/ability')
const { ability, build } = taskFunctions;

const test = createSystem({
    name: 'Test',
    type: 'build',
    buildOrder: [
        [13, build(SUPPLYDEPOT)],
        [13, build(BARRACKS)],
        [16, ability(MORPH_ORBITALCOMMAND)],
    ],

Probably it would be better to support the following:

const { ORBITALRELAY } = require('@node-sc2/core/constants/upgrade')
const { ability, build } = taskFunctions;

const test = createSystem({
    name: 'Test',
    type: 'build',
    buildOrder: [
        [13, build(SUPPLYDEPOT)],
        [13, build(BARRACKS)],
        [16, upgrade(ORBITALRELAY)],
    ],