Feat | generate token for secret

[n370]

Closes: #5

This PR adds:

• A back-end service wrapper mostly ported over from optic-web.
• A bare bones <Secret /> component with a button to trigger the token generation.

[n370]

@simoneb I guess I'm leaving this here for now. The code is functional and does the job of talking to the server to get a token. It works fine. There are a couple of things missing though.

optic-expo/tests/Main.test.js

Lines 107 to 155 in f06fff2

	it('should allow an authenticated user to scan a QR code', async () => {
	const mockSecret = {
	secret: 'mock-qr-secret',
	account: 'test',
	issuer: '',
	uid: 'uid',
	}
	mockUseAuthRequest({
	type: 'success',
	params: {
	id_token: 'token',
	},
	})
	const addSecretsMock = jest.fn()
	useSecrets.mockReturnValue({
	isInitialized: true,
	secrets: [],
	add: addSecretsMock,
	})
	const getIdTokenMock = jest.fn().mockResolvedValue('id-token')
	firebase.auth().onAuthStateChanged = jest.fn(callback =>
	callback({
	name: 'user',
	uid: 'uid',
	getIdToken: getIdTokenMock,
	})
	)
	const { queryByText, getByA11yLabel } = renderWithTheme({
	ui: <Main />,
	})
	await waitFor(() => expect(getIdTokenMock).toHaveBeenCalled())
	expect(queryByText('Your Tokens')).not.toBeNull()
	const showActionsButton = getByA11yLabel('show-actions')
	fireEvent.press(showActionsButton)
	const scanCodeButton = getByA11yLabel('Scan QR Code')
	fireEvent.press(scanCodeButton)
	await waitFor(() => expect(addSecretsMock).toHaveBeenCalledWith(mockSecret))
	})

This unit test is for instance passing but not without logging an error to the console. I spent some time with it trying to figure out what was going on but at this point I think we should consider breaking it down into smaller tests. This one is already doing too much imho.

We're also missing writing new unit tests at least for the new class being added here.

[salmanm]

#80 included commits from this PR, so closing...