Make common ancestor for CsvReaderContext and CsvWriterContext

[SPC-code]

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It is required to create a common reading and writing rules. For example, TSV rule could look like this:

val TSV: CsvContext.()->Unit = {
    charset = "ISO_8859_1"
    quoteChar = '"'
    delimiter = '\t'
    escapeChar = '\\'
}

It could be used as:

csvReader(TSV)