Add support for #RRGGBB hex colour values for embed

[Wolfdv1]

The embed creator I initially used gave hex rather than the decimal representation, this function checks against a quick regex to see if #RRGGBB hex value has been used and if so converts it to decimal and returns the string as normal.

Example:

jsonColorHexToDec("{\r\n  \"author\": {\r\n    \"name\": \"%name%\",\r\n    \"icon_url\": \"https://crafthead.net/avatar/%uuid%\"\r\n  },\r\n  \"description\": \"%msg%\",\r\n  \"color\": \"#4F545C\"\r\n}")

gives:

{\r\n  \"author\": {\r\n    \"name\": \"%name%\",\r\n    \"icon_url\": \"https://crafthead.net/avatar/%uuid%\"\r\n  },\r\n  \"description\": \"%msg%\",\r\n  \"color\": \"5198940\"\r\n}

And if decimal is given originally, no changes are made.
Currently if a Hex value #RRGGBB is given the following crash error is given:

java.lang.NumberFormatException: For input string: "#4F545C"
        at java.base/java.lang.NumberFormatException.forInputString(Unknown Source) ~[?:?]
        at java.base/java.lang.Integer.parseInt(Unknown Source) ~[?:?]
        at java.base/java.lang.Integer.parseInt(Unknown Source) ~[?:?]
        at knot/net.dv8tion.jda.api.utils.data.DataObject.get(DataObject.java:913) ~[de_erdbeerbaerlp_dcintegration_common-3.1.0-55dc154341f71a65.jar:?]
        at knot/net.dv8tion.jda.api.utils.data.DataObject.getInt(DataObject.java:575) ~[de_erdbeerbaerlp_dcintegration_common-3.1.0-55dc154341f71a65.jar:?]
        at knot/net.dv8tion.jda.api.EmbedBuilder.fromData(EmbedBuilder.java:115) ~[de_erdbeerbaerlp_dcintegration_common-3.1.0-55dc154341f71a65.jar:?]
        at knot/de.erdbeerbaerlp.dcintegration.common.storage.Configuration$EmbedMode$EmbedEntry.toEmbedJson(Configuration.java:238) ~[de_erdbeerbaerlp_dcintegration_common-3.1.0-55dc154341f71a65.jar:?]

The above function would prevent this, and also may be altered for formats of 0xRRGGBB along with #RRGGBB as needed.

ps, the function itself is tested standalone- but has not been integration tested