feat: add support for chapters & video heatmap

[LuanRT]

Description

This adds support for chapters & heatmap. Here are a few examples of how this can be used:

Chapters:

import { Innertube, UniversalCache } from 'youtubei.js';

(async () => {
  const yt = await Innertube.create({ cache: new UniversalCache() });

  const info = await yt.getInfo('5DrSU72hOUQ');

  const markers_map = info.player_overlays?.decorated_player_bar?.player_bar?.markers_map;

  const chapters = (
    markers_map?.get({ marker_key: 'AUTO_CHAPTERS' }) ||
    markers_map?.get({ marker_key: 'DESCRIPTION_CHAPTERS' })
  )?.value.chapters;

  if (chapters) {
    console.log('Chapters:\n');
    for (const chapter of chapters) {
      console.log(chapter.title.toString(), ' - Starts in ', Math.round(chapter.time_range_start_millis / 1000), 'seconds');
    }
  }
})();

Output:

Chapters:

Intro  - Starts in  0 seconds
Paul and Morgan  - Starts in  125 seconds
My Comment  - Starts in  1763 seconds
Outro  - Starts in  1851 seconds

---

Heatmap:

import { Innertube, UniversalCache } from 'youtubei.js';

(async () => {
  const yt = await Innertube.create({ cache: new UniversalCache() });

  const info = await yt.getInfo('5DrSU72hOUQ');

  const markers_map = info.player_overlays?.decorated_player_bar?.player_bar?.markers_map;
  const heatmap = markers_map?.get({ marker_key: 'HEATSEEKER' })?.value.heatmap;

  if (heatmap) {
    const heatmap_columns = heatmap.heat_markers.map((marker) => '█'.repeat(Math.round(marker.heat_marker_intensity_score_normalized * 10) + 1).split(''));

    let last_col_index = heatmap_columns.reduce((prev, curr) => {
      if (curr.length > prev.length) {
        return curr;
      }
      return prev;
    }).length;

    console.log('\nHeatmap:\n', '-'.repeat(heatmap_columns.length + 2));

    // Draw the heatmap horizontally
    while (last_col_index !== -1) {
      let row = '';

      for (const col of heatmap_columns) {
        row += col[last_col_index] || ' ';
      }

      console.log('|', row, '|', last_col_index + 1);

      row = '';

      last_col_index--;
    }
  }
})();

Output:

Heatmap:
 ------------------------------------------------------------------------------------------------------
|                                                                                                      | 12
|            █                                                                              █          | 11
|            █                                                                              █          | 10
| █          █                                                                              █          | 9
| █          ██                                                                             █          | 8
| █          ██                                              ███      █                     █          | 7
| █       █ ███                                              ███      █                     █          | 6
| █      ██ ███                                     █        ███      █                     █          | 5
| ██    ███ ███   █                                 █        ███      █                     █          | 4
| ██    ███████  ██                   █            ██ █     █████     █                    ██    █     | 3
| ████ █████████████           █████ ████████████████████ ███████    ██   █   █ █     ██   ██  █ ███   | 2
| ████████████████████████████████████████████████████████████████████████████████████████████████████ | 1

Related: yt-dlp/yt-dlp#3888

Type of change

Please delete options that are not relevant.

• New feature (non-breaking change which adds functionality)

Checklist:

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes
• I have checked my code and corrected any misspellings