`@ElementTemplate` annotation API enhancements

[chillleader]

Is your feature request related to a problem? Please describe.

2 improvements are requested for the annotation-based element template generator API:

• [x] Allow defining custom element type (e.g. for script tasks), currently it's always bpmn:ServiceTask
• [ ] @OutboundConnector annotation is currently unaware of the input data type (inputDataClass), unlike the @ElementTemplateannotation. It would be nice to implement this to avoid defining inputVariables manually.
• [ ] Support generation of multiple element templates for different element types for a single connector

Describe the solution you'd like

@ElementTemplate(
    id = "aws-dynamodb-connector-aws-dynamodb",
    type = "bpmn:ScriptTask"       // optional value, defaults to service task
    name = "Generated AWS DynamoDB Connector",
    version = 1,
    description = "Generated AWS DynamoDB Connector",
    inputDataClass = AwsDynamoDbRequest.class)

@OutboundConnector(
    name = "AWS DynamoDB",
    inputDataClass = AwsDynamoDbRequest.class, // the same param can then be removed from `@ElementTemplate`
    type = "io.camunda:aws-dynamodb:1")

Describe alternatives you've considered

None

Additional context

None

[chillleader]

Partially implemented in #1353: now it is possible to specify custom elementType and appliesTo.

[mattli2024]

@chillleader - is this still relevant? Can you review