(Android)Added option to make a notification ongoing(so it can't be swiped away)

[TheDutchDev]

Found this issue(#1147) while looking for a solution myself, didn't find one so decided to add my own based on the information given in that issue.

One can specify whether they want the notification to be ongoing(so it can't be swiped away) from the javascript side now.

Example(copy-pasted mostly from the docs):

const notifs = await LocalNotifications.schedule( {
    notifications: [
        {
            title: "Title",
            body: "Body",
            id: 1,
            schedule: { at: new Date( Date.now() + 1000 ) },
            sound: null,
            attachments: null,
            actionTypeId: "",
            extra: null,
            ongoing: true, // << The new bit
            autoCancel: false // << see edit below
        }
    ]
} );

EDIT: Also added option to set autoCancel manually. default is still set to true as it was before.

[carlpoole]

Thank you for your contribution. I merged in master and tested.