Add a max_size field to the TCP source config parser syntax.

[mnp]

This PR adds an additional field to TCPSourceConfigCLIParser such that you can specify a maximum message size per source. The format is either source_name@host:service or source_name@host:service:max_size. This should be backward compatible to existing applications.

For example, an app might have a command line like this:

    --in foo-source@0.0.0.0:7100,bar-source@0.0.0.0:7102:200000000

where foo-source has the default size of 16384 and bar-source 200 MB.

[CLAassistant]

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