Integration tests for LOOKUP JOIN over wider range of data types (#126150)

This test suite tests the lookup join functionality in ESQL with various data types.

For each pair of types being tested, it builds a main index called "index" containing a single document with as many fields as types being tested on the left of the pair, and then creates that many other lookup indexes, each with a single document containing exactly two fields: the field to join on, and a field to return.

The assertion is that for valid combinations, the return result should exist, and for invalid combinations an exception should be thrown. If no exception is thrown, and no result is returned, our validation rules are not aligned with the internal behaviour (ie. a bug).

Since the `LOOKUP JOIN` command requires the match field name to be the same between the main index and the lookup index, we will have field names that correctly represent the type of the field in the main index, but not the type of the field in the lookup index. This can be confusing, but it is important to remember that the field names are not the same as the types.

Author: craigtaverner

x-pack/plugin/esql/build.gradle

@@ -53,6 +53,7 @@ dependencies {
   testImplementation project(path: xpackModule('enrich'))
   testImplementation project(path: xpackModule('spatial'))
   testImplementation project(path: xpackModule('kql'))
+  testImplementation project(path: xpackModule('mapper-unsigned-long'))
 
   testImplementation project(path: ':modules:reindex')
   testImplementation project(path: ':modules:parent-join')