[Console] Language Markers

[jloleysens]

Describe the feature:

Console supports three different languages: the console language itself (combination of cURL-like and XJSON), Painless and Elasticsearch SQL. Currently, syntax highlighting is automatically inferred from surrounding text like:

POST _search
{
...
    "script": """
         // Here is some Painless
    """
...
}

# and

POST _sql
{
...
    "query": """
       -- This is some Elasticsearch SQL
    """
...
}

The common denominator being """. The result has been a collection of lexer rules that are not very portable to other pieces of text in the editor. To make the lexer rules more simple and offer the end user more control over highlighting in different regions of text we could do something like:

POST _another_endpoint
{
...
    "any_key": """painless
         // Here is some Painless
    """
...
}

# and

POST _something_else
{
...
    "some_key": """sql
       -- This is some Elasticsearch SQL
    """
...
}

Describe a specific use case for the feature:

• Giving the user a well defined way to get syntax highlighting for a supported language at any point in the text.
• The addition of """xlang markers gives maintainers a much better way of introducing new languages to the lexer rules without needing to make them more complex.
• We can advertise supported languages by providing autocomplete options after """
• Having simpler rules makes them easier to test manually.

[elasticmachine]

Pinging @elastic/es-ui (Team:Elasticsearch UI)

[jloleysens]

The Monaco-based editor supports """sql Type your SQL here """ at the moment.

We will need to add collapseStringLiteral support for these cases.

[elasticmachine]

Pinging @elastic/kibana-management (Team:Kibana Management)