CLI: Add command to display the list of supported file formats

[lastzero]

As a user with a variety of file formats in my library, I would like to check them against a list of supported formats without having to read source code or external documentation.

Implementing this seems like a quick win since we need this for our documentation anyway and don't have time to manually update the list every time something changes.

To show all supported formats (-s hides the description to make the output more compact, the -n flag removes the text wrapping so that the result can be copied directly into our docs as it is a valid Markdown table):

$ photoprism show formats

| Format |          Description           |  Type   |           Extensions           |
|--------|--------------------------------|---------|--------------------------------|
| BMP    | Bitmap                         | Image   | .bmp                           |
| GIF    | Graphics Interchange Format    | Image   | .gif                           |
| HEIF   | High Efficiency Image File     | Image   | .heic, .heif                   |
|        | Format                         |         |                                |
| JPG    | JPEG (Joint Photographic       | Image   | .jfi, .jfif, .jif, .jpe,       |
|        | Experts Group)                 |         | .jpeg, .jpg, .thm              |
| MPO    | Stereoscopic 3D Format based   | Image   | .mpo                           |
|        | on JPEG                        |         |                                |
| PNG    | Portable Network Graphics      | Image   | .pn, .png                      |
| TIFF   | Tag Image File Format          | Image   | .tif, .tiff                    |
| WEBP   | Google WebP                    | Image   | .webp                          |
| RAW    | Unprocessed Image Data         | Raw     | .3fr, .ari, .arw, .bay, .cap,  |
|        |                                |         | .cr2, .cr3, .crw, .data, .dcr, |
|        |                                |         | .dcs, .dng, .drf, .eip, .erf,  |
|        |                                |         | .fff, .gpr, .iiq, .k25, .kdc,  |
|        |                                |         | .mdc, .mef, .mos, .mrw, .nef,  |
|        |                                |         | .nrw, .obm, .orf, .pef, .ptx,  |
|        |                                |         | .pxn, .r3d, .raf, .raw, .rw2,  |
|        |                                |         | .rwl, .rwz, .sr2, .srf, .srw,  |
|        |                                |         | .x3f                           |
| AAE    | Apple Image Edits              | Sidecar | .aae                           |
| JSON   | Serialized JSON Data           | Sidecar | .json                          |
|        | (Exiftool, Google Photos)      |         |                                |
| MD     | Markdown Formatted Text        | Sidecar | .markdown, .md                 |
| TOML   | Serialized TOML Data (Tom's    | Sidecar | .toml                          |
|        | Obvious, Minimal Language)     |         |                                |
| TXT    | Plain Text                     | Sidecar | .txt                           |
| XML    | Extensible Markup Language     | Sidecar | .xml                           |
| XMP    | Adobe Extensible Metadata      | Sidecar | .xmp                           |
|        | Platform                       |         |                                |
| YML    | Serialized YAML Data (Config,  | Sidecar | .yaml, .yml                    |
|        | Metadata)                      |         |                                |
| 3G2    | Multimedia Container for 3G    | Video   | .3g2                           |
|        | CDMA2000, based on 3GP         |         |                                |
| 3GP    | MPEG-4 Part 12, Mobile         | Video   | .3gp                           |
|        | Multimedia Container           |         |                                |
| AV1    | Alliance for Open Media        | Video   | .av1                           |
| AVC    | H.264, Advanced Video Coding,  | Video   | .avc                           |
|        | MPEG-4 Part 10                 |         |                                |
| AVI    | Microsoft Audio Video          | Video   | .avi                           |
|        | Interleave                     |         |                                |
| FLV    | Flash Video                    | Video   | .f4v, .flv                     |
| HEVC   | H.265, High Efficiency Video   | Video   | .hevc                          |
|        | Coding                         |         |                                |
| MKV    | Matroska Multimedia Container  | Video   | .mkv                           |
| MOV    | Apple QuickTime                | Video   | .mov, .qt                      |
| MP2    | H.262, H.222, MPEG-2           | Video   | .mp2, .mpv                     |
| MP4    | MPEG-4 Part 14 Multimedia      | Video   | .m4v, .mp, .mp4                |
|        | Container                      |         |                                |
| MPG    | MPEG (Moving Picture Experts   | Video   | .mpeg, .mpg                    |
|        | Group)                         |         |                                |
| MTS    | AVCHD (Advanced Video Coding   | Video   | .mts                           |
|        | High Definition)               |         |                                |
| OGV    | Ogg Media by Xiph.Org          | Video   | .ogg, .ogv, .ogx               |
| WEBM   | Google WebM                    | Video   | .webm                          |
| WMV    | Windows Media                  | Video   | .wmv                           |

[rabotond]

Tested. Indeed the new command works and lists formats.