Fix improve cgoreceiver log format

[NeJan2020]

Optimized the log output of CgoReceiver to display the specific value in UserAttribute

Description

Print Specific Value of UserAttributes rather than base64 Encoding.

Only print printable character (ASCII char code from 32 to 126) for ByteBuffer , other character will be replaced by .
The max length is 200, and extra bytes will be count, such as <POST /test?sleep=800 HTTP/1.1xxxxx(69 bytes more)>

How Has This Been Tested?

Running tool: /usr/local/go/bin/go test -timeout 60m -run ^TestTextEvent$ github.com/Kindling-project/kindling/collector/pkg/model

=== RUN   TestTextEventa
--- PASS: TestTextEvent (0.00s)
PASS
ok      github.com/Kindling-project/kindling/collector/pkg/model        0.010s

Here is some examples.

{Name:read Category:3 ParamsNumber:3 UserAttributes:[starttime:1666085694803271345 data:<POST /test?sleep=800 HTTP/1.1...Host: 10.10.103.148:9000...Content-Type: application/x-www-form-urlencoded ...xxxxjkajdnaksndandlkajelkqjweklqwjeklqjlwejklasdas...qwelkqnmwlkenqlwenqwnekqkwelkqmnwlekq(69 bytes more)>] Ctx:{ThreadInfo:{Pid:22592 Tid:22592 Uid:0 Gid:0 Comm:node ContainerId:123123 ContainerName:test} FdInfo:{Num:19 TypeFd:3 Filename:tmp Directory:/root Protocol:1 Role:true Sip:[16777343] Dip:[16777343] Sport:39620 Dport:37093 Source:0 Destination:0}} Latency:100 Timestamp:160000}

[dxsup]

Only print char in [a-zA-Z0-9] and . / \ @ ? - = for ByteBuffer now, other char will be replaced by ,

I think . is better because Sysdig does like it which we have been familiar with.

and the max length is 80

80 is not enough since we set SNAPLEN to 1000 by default. We better set the max length to 200 at least and add a sign if there are more than 200 bytes to explicitly tell users we truncate the bytes - maybe we could add an xxx bytes more sign at the tail.