Added tests for most of the methods in FunctionUtil.

[bubblobill]

Identify the Bug or Feature request

fixes #5956
closes #5956

Description of the Change

Missing tests for: i.e. I couldn't work out how to get them to fly.

• FunctionUtil.experimentalWarning()
• FunctionUtil.getTokenFromParam()
• FunctionUtil.getZoneRendererFromParam()
• FunctionUtil.getZoneRenderer()
• FunctionUtil.getAssetKeyFromString()
• FunctionUtil.blockUntrustedMacro()

Added tests for;

• checkNumberParam()

• delimitedResult()

• getBooleanValue()

• getPaintFromString()

• paramAsBoolean()

• paramAsString()

• paramAsInteger()

• paramAsDouble()

• paramAsFloat()

• paramAsBigDecimal()

• paramFromStrPropOrJsonAsJsonObject()

• paramAsJson()

• paramAsJsonObject()

• paramAsJsonArray()

• paramConvertedToJsonArray()

• paramConvertedToJson()

• jsonWithLowerCaseKeys()

• validateKeyNames()

Possible Drawbacks

Macros relying on dodgy flavours might fail the taste test, though unlikely.

Release Notes

Improved macro argument processing

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This change is 

[bubblobill]

Tests failing before fixes:

• FunctionUtilTest > paramFromStrPropOrJsonAsJsonObject() FAILED
• FunctionUtilTest > FunctionUtil.paramAsBoolean() FAILED
• FunctionUtilTest > FunctionUtil.paramAsDouble() FAILED
• FunctionUtilTest > FunctionUtil.paramAsBigDecimal() FAILED
• FunctionUtilTest > FunctionUtil.getBooleanValue() FAILED
• FunctionUtilTest > FunctionUtil.paramAsFloat() FAILED
• FunctionUtilTest > FunctionUtil.paramAsInteger() FAILED