[CLI] New options, fixes, update README

[superbonaci]

This PR fixes several issues reported by users and adds requested features.

Changes to mode tsmerge:

• Fix bug that adds all lines in .m3u8 as files
• Add new option -f to ignore files from the playlist that are missing in the filesystem.

Changes to mode videodownload:

• Add -K option to keep complete cache folder
• Add -k option to keep cache folder but .ts parts
• Make -o optional to skip converting output.ts to another file
• Add -F option to skip free space check
• Add -p option to download only .ts parts, metadata.txt and playlist.m3u8 to cache folder
• Add --tbn option to set specific tbn to output
• Add short option -c for --temp-path
• Add short option -a for --oauth
• Update space check function to report how much space is required when is less than required. Not accurate in certain cases. A few samples included in comment
• Create playlist.m3u8 and metadata.txt during "Fetching Video Info", before downloading any .ts part
• Dynamically adjust the the number of progress bars according to options involved

Changes to mode clipdownload:

• Add --tbn option to set specific tbn to output

Add a newline after operation is completed, to put the shell prompt in a new line after TwitchDownloaderCLI ends (starship adds a new line if needed but this is not standard this is why some people don't realize there's a bug):

• VideoDownloader.cs
• TsMerger.cs
• ChatDownloader.cs
• ChatDownloader.cs

TwitchDownloaderCLI/README.md:

• Explain better crop, crop beginning and crop ending
• Explain better cache storage
• Add global arguments section
• An explanation is still missing to explain that -b and -e don't cut always by I-frame and what's the issue with that
• An explanation is still missing to explain that -b and -e don't adjust chapters relative to output mp4/m4a file instead of the whole VOD.

TwitchDownloaderCore/Extensions/M3U8Extensions.cs:

• Add best quality to return the same as chunked or source.
• Add worst quality to select the lowest video quality.