feat: Add pause and resume methods

[Lechevallier]

Is your feature request related to a problem? Please describe:
I wish this plugin would allow to pause and resume the read.
For example, speechSynthesis allow this, but unfortunately this is not supported on android browser.

Describe the solution you'd like:
As a developer, I expect the 2 following functions to be added to the TextToSpeechPlugin interface:

export interface TextToSpeechPlugin {
    ...
    /**
     * Pause the read.
     */
    pause(): Promise<void>;
    /**
     * Resume the read.
     */
    resume(): Promise<void>;

Describe alternatives you've considered:
As said before, I tried speechSynthesis, but this is not supported for android browser.

window.speechSynthesis.start("Hello world");
window.speechSynthesis.pause();
window.speechSynthesis.resume();

Additional context:
Expected behaviour:

• open this demo
• click "Interrupt" to start the read
• click the play/pause button to pause the read
• click the play/pause button to resume the read