YAML input in trigger UI

### Description I work in a project where having a yaml input in the web UI (instead of json -> which is in the case of object type param) is beneficial. I understand that airflow support multiple datatypes - ints, strings, list/arrays, and objects. Is it possible to also have yaml as a input. On a sidenote: I thought of interpreting multiline input, i.e., list of strings as my input, which I can join and interpret as yaml. However, airflow tends to remove trailing white spaces in string list items, thereby losing indentation information. example: a multiline array input of ``` a: b: c ``` is incorrectly transformed to yaml of this form: ```yaml {a: None, b: c} ``` instead of: ```yaml {a: {b: c}} ``` is this the intended purpose or is this is a bug?? ### Use case/motivation I would like a human readable input, where the user can copy paste their yaml files in a text box. ### Related issues I thought of interpreting multiline input, i.e., list of strings as my input, which I can join and interpret as yaml. However, airflow tends to remove trailing white spaces in string list items, thereby losing indentation information. ### Are you willing to submit a PR? - [ ] Yes I am willing to submit a PR! ### Code of Conduct - [x] I agree to follow this project's [Code of Conduct](https://github.com/apache/airflow/blob/main/CODE_OF_CONDUCT.md)