Compatibility with elasticsearchconnector 8.x-7.x

Created a patch which works with D 9.x Elastic 7 and php 8.1

Please review it.

Litle finetuning to #19

Using exposed filter (>=, <= operators) for date fields and got:
Error: Call to undefined method Drupal\search_api\Query\ConditionGroup::getField() in elasticsearch_connector_autocomp_elasticsearch_connector_search_api_query_alter()

#20 patch modified.

The patch needs updating to work with elasticsearch_connector 8.x-7.x.

PrepareIndexEvent::getIndex doesn't exist, it should be PrepareIndexEvent::getIndexName instead. There may be other changes needed. If I have time today I will see if I can update the patch.

For one of our projects, we use the patch from #15, which worked fine. But due to deprecation of the boost-parameter, in combination with Elasticsearch 8, an error will occur:

[error]  Message: {"error":{"root_cause":[{"type":"mapper_parsing_exception","reason":"Unknown 
parameter [boost] on mapper 
[rendered_item]"}],"type":"mapper_parsing_exception","reason":"Failed to 
parse mapping: Unknown parameter [boost] on mapper 
[rendered_item]","caused_by":{"type":"mapper_parsing_exception","reason":"Unknown 
parameter [boost] on mapper [rendered_item]"}},"status":400}

When the boost-parameter is omitted, it works fine. Therefore I've rerolled the patch from #15, without the boost property.
So this is not a reroll of #21 and therefore this still needs work.

Re-rolling patch #24 for latest version of dev

We have tested and are using the patch 3072676-25.patch from comment # 25.