Added ffmpeg progress bar via fluent-ffmpeg and progress libs (#57)

* Add fluent-ffmpeg back and cross-platform progress bar

* Repo clean up

Move ts files to src, build and output js files to build folder

* Do not print messages when exit code is 0

this is triggered by signal events

Co-authored-by: kylon <kylonux@gmail.com>

src/Types.ts

@@ -0,0 +1,36 @@
+export type Session = {
+    AccessToken: string;
+    ApiGatewayUri: string;
+    ApiGatewayVersion: string;
+}
+
+
+export type Metadata = {
+    date: string;
+    duration: number;
+    title: string;
+    playbackUrl: string;
+    posterImage: string;
+}
+
+
+interface Errors {
+    [key: number]: string
+}
+
+// I didn't use an enum because there is no real advantage that i can find and
+// we can't use multiline string for long errors
+// TODO: create better errors descriptions
+export const Errors: Errors = {
+    22: 'FFmpeg is missing. \n' +
+        'Destreamer requires a fairly recent release of FFmpeg to work properly. \n' +
+        'Please install it with your preferred package manager or copy FFmpeg binary in destreamer root directory. \n',
+
+    33: 'cannot split videoID from videUrl \n',
+
+    44: 'couldn\'t evaluate sessionInfo in the page \n',
+
+    55: 'running in an elevated shell \n',
+
+    66: 'no valid URL in the input \n'
+}