Add mode as dynamic field

[bah07]

Related issue	QA issue	Documentation issue
#4799	wazuh/wazuh-qa#673	wazuh/wazuh-documentation#2407

Description

This pull request adds the mode field to the FIM alerts. It also makes alerts more consistent deleting the hyphen from the real-time alerts, leaving three possibilities: scheduled|realtime|whodata.
This pull request closes #4799.

Logs/Alerts example

{
    "id": "1587466043.151965",
    "full_log": "File '/test/file_7' added\nMode: realtime\n",
    "syscheck": {
        "path": "/test/file_7",
        "mode": "realtime",
        "size_after": "0",
        "perm_after": "rw-r--r--",
        "uid_after": "0",
        "gid_after": "0",
        "md5_after": "d41d8cd98f00b204e9800998ecf8427e",
        "sha1_after": "da39a3ee5e6b4b0d3255bfef95601890afd80709",
        "sha256_after": "e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855",
        "uname_after": "root",
        "gname_after": "root",
        "mtime_after": "2020-04-21T10:47:23",
        "inode_after": 34033987,
        "event": "added"
    },
    "decoder": {
        "name": "syscheck_new_entry"
    },
    "location": "syscheck"
}

Tests

• Compilation without warnings in every supported platform
  • Linux
  • Windows
  • MAC OS X
• Source installation
• Package installation
• Source upgrade
• Package upgrade
• Review logs syntax and correct language
• QA templates contemplate the added capabilities

• Memory tests for Linux
  • Scan-build report
  • Coverity
  • Valgrind (memcheck and descriptor leaks check)
  • Dr. Memory
  • AddressSanitizer

• Added unit tests (for new features)