Improve type errors in painless with user-friendly suggestions

[stu-elastic]

It can be hard to know the types one is working with in a painless script without having mappings in ones head.

Say field is a date and you have the following script:

doc['field'] + 5

Our current error is:
Cannot apply [+] operation to types [org.elasticsearch.index.fielddata.ScriptDocValues.Dates] and [java.lang.Integer].

For common failures, particularly around dates, we can provide a more human error, such as:

"You tried to add a number to a Date. Check out this link to learn how to convert a date to epoch time."

cc: @bmcconaghy @cjcenizal

[elasticmachine]

Pinging @elastic/es-core-infra (:Core/Infra/Scripting)