[FR] ES|QL remote validation support newline split indices

[eric-forte-elastic]

Repository Feature

None

Problem Description

Currently rules with newline split indices (e.g. #5340) do not have their indices parsed correctly.

E.g.

Given a rule with the following from ES|QL line:

from
  logs-network_traffic.http-*,
  logs-network_traffic.tls-*,
  logs-nginx.access-*,
  logs-apache.access-*,
  logs-apache_tomcat.access-*,
  logs-iis.access-*

get_esql_query_indices will return a sources_list of the following: ['logs-network_traffic.http-*', ''] which includes only the first index and an empty name index.

Desired Solution

No response

Considered Alternatives

The regex definition FROM_SOURCES_REGEX should support multi-line index definitions. E.g. something like:

FROM_SOURCES_REGEX = re.compile(
    r"^\s*FROM\s+(?P<sources>(?:.+?(?:,\s*)?\n?)+?)\s*(?:\||\bmetadata\b|//|$)",
    re.IGNORECASE | re.MULTILINE
)

Additional Context

No response