fix issues in taosdump.c

[xiaopingcs]

Bug Description
fix issues found by Coverity Scan in taosdump.c

To Reproduce
Steps to reproduce the behavior:
N/A

Expected Behavior
fix following issues found by Coverity Scan in taosdump.c

1. String not null terminated High TDengine/src/kit/taos-tools/src/benchUtil.c postProceSql
2. Resource leak High TDengine/src/kit/taos-tools/src/taosdump.c parse_json_to_recordschema
3. Resource leak High TDengine/src/kit/taos-tools/src/taosdump.c dumpInAvroDataImpl
4. Resource leak High TDengine/src/kit/taos-tools/src/taosdump.c dumpInAvroDataImpl
5. Uninitialized scalar variable High TDengine/src/kit/taos-tools/src/taosdump.c checkFileExistsExt
6. Uninitialized pointer read High TDengine/src/kit/taos-tools/src/taosdump.c createMTableAvroHeadImp
7. Resource leak High TDengine/src/kit/taos-tools/src/taosdump.c dumpNormalTablesOfStb
8. Array compared against 0 Medium TDengine/src/kit/taos-tools/src/taosdump.c dumpInAvroTbTagsImpl
9. Uninitialized pointer read High TDengine/src/kit/taos-tools/src/taosdump.c dumpCreateTableClauseAvro
10. Uninitialized pointer read High TDengine/src/kit/taos-tools/src/taosdump.c dumpCreateTableClauseAvro
11. Resource leak High TDengine/src/kit/taos-tools/src/taosdump.c parse_json_for_inspect
12. Argument cannot be negative Medium TDengine/src/kit/taos-tools/src/taosdump.c createMTableAvroHead
13. Resource leak High TDengine/src/kit/taos-tools/src/taosdump.c createMTableAvroHead
14. Uninitialized pointer read High TDengine/src/kit/taos-tools/src/taosdump.c createMTableAvroHeadImp
15. Uninitialized pointer read High TDengine/src/kit/taos-tools/src/taosdump.c createMTableAvroHeadImp
16. Array compared against 0 Medium TDengine/src/kit/taos-tools/src/taosdump.c dumpInAvroDataImpl
17. Explicit null dereferenced Medium TDengine/src/kit/taos-tools/src/taosdump.c dumpInAvroNtbImpl

Screenshots
N/A

Environment (please complete the following information):
N/A

Additional Context
Coverity Scan Dashboard for TDengine: https://scan.coverity.com/projects/tdengine?tab=overview

[fansehep]

please assign it to me. this my pr taosdata/taos-tools#223