v.colors.out: Add JSON support

[NishantBansal2003]

fixes: #4660

Used Parson to add JSON output format support to the v.colors.out module.

Description

• Added a new format option, allowing users to specify the output format:
• format=plain for the current output format.
• format=json for JSON output.
• Introduced the color_format option to specify the color format for JSON output. Supported values for color_format include rgb, hex, hsv, and triplet.

Example JSON Output

The JSON output appears as follows:

[
        {"value": 1, "hex": "#00BFBF"},
        {"value": 20.8, "hex": "#00FF00"},
        {"value": 40.6, "hex": "#FFFF00"},
        {"value": 60.4, "hex": "#FF7F00"},
        {"value": 80.2, "hex": "#BF7F3F"},
        {"value": 100, "hex": "#C8C8C8"},
        {"value": "nv", "hex": "#FFFFFF"},
        {"value": "default", "hex": "#FFFFFF"},
]

[cwhite911]

How about setting the JSON key for the returned color to color instead of hex, rgb, hsv, and triplet because it doesn't appear that you can request multiple color formats at once.

[NishantBansal2003]

How about setting the JSON key for the returned color to color instead of hex, rgb, hsv, and triplet because it doesn't appear that you can request multiple color formats at once.

Yes, that will be great. I have made the necessary changes. PTAL.

[cwhite911]

@NishantBansal2003 looks good to me!

[petrasovaa]

Works great!