Non-java clients identity pool extension comma parsing

[PratRanj07]

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This PR intends to implement CSV format parsing for SASL OAuthbearer Extensions.

Supported extension format examples:

'sasl.oauthbearer.extensions':'logicalCluster=l1_value,identityPoolId=i1_value'
'sasl.oauthbearer.extensions':'logicalCluster=l1_value,"identityPoolId=i1_value,i2_value",myOtherExtension=myExtensionValue'

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[anchitj]

Thanks @PratRanj07. Some minor comments, but overall looks good. Let's verify manually with a cluster too.

[anchitj]

Also verify if the extensions have spaces can they be parsed correctly and interpreted by the broker. Like identityPoolId=p1, p2