use new modbus event prototypes for Zeek v6.1.0+

[mmguero]

The Zeek v6.1.0 release states:

The ModBus file record read and write events now provide the full data from
the request and response messages as part of the event data.

The full PDU length was added to the ModBusHeader record type passed with
all of the ModBus events.

This commit handles the deprecated function warnings:

warning in /opt/zeek/share/zeek/site/packages/icsnpp-modbus/main.zeek, line 761 and /opt/zeek/share/zeek/base/bif/plugins/Zeek_Modbus.events.bif.zeek, line 220: use of deprecated 'modbus_read_file_record_request' prototype: Remove in v7.1. Use the version that takes a byte_count and vector of references (event(c:connection, headers:ModbusHeaders))
warning in /opt/zeek/share/zeek/site/packages/icsnpp-modbus/main.zeek, line 786 and /opt/zeek/share/zeek/base/bif/plugins/Zeek_Modbus.events.bif.zeek, line 234: use of deprecated 'modbus_read_file_record_response' prototype: Remove in v7.1. Use the version that takes a byte_count and vector of references (event(c:connection, headers:ModbusHeaders))
warning in /opt/zeek/share/zeek/site/packages/icsnpp-modbus/main.zeek, line 811 and /opt/zeek/share/zeek/base/bif/plugins/Zeek_Modbus.events.bif.zeek, line 248: use of deprecated 'modbus_write_file_record_request' prototype: Remove in v7.1. Use the version that takes a byte_count and vector of references (event(c:connection, headers:ModbusHeaders))
warning in /opt/zeek/share/zeek/site/packages/icsnpp-modbus/main.zeek, line 836 and /opt/zeek/share/zeek/base/bif/plugins/Zeek_Modbus.events.bif.zeek, line 262: use of deprecated 'modbus_write_file_record_response' prototype: Remove in v7.1. Use the version that takes a byte_count and vector of references (event(c:connection, headers:ModbusHeaders))