[wasm] The way of getting the path of `runtimeconfig.json` file is not always reliable

[fanyang-mono]

In wasm build process, the path of runtimeconfig.json file was generated based the location of the main app assembly. This would work with the assumption that runtimeconfig.json file lived in the same folder as the main app assembly file. This assumption was broken when enabling IL trim by default for wasm apps in my PR (#90436). When the main app assembly file gets trimmed, the newly generated trimmed assembly lives in a separated directory than the runtimeconfig.json file. We need a more robust way of finding runtimeconfig.json file.

Tagging subscribers to 'arch-wasm': @lewing
See info in area-owners.md if you want to be subscribed.

Issue Details

---

In wasm build process, the path of runtimeconfig.json file was generated based the location of the main app assembly. This would work with the assumption that runtimeconfig.json file lived in the same folder as the main app assembly file. This assumption was broken when enabling IL trim by default for wasm apps in my PR (#90436). When the main app assembly file gets trimmed, the newly generated trimmed assembly lives in a separated directory than the runtimeconfig.json file. We need a more robust way of finding runtimeconfig.json file.

Author:	fanyang-mono
Assignees:	radical
Labels:	arch-wasm
Milestone:	9.0.0

[radical]

The assumption is correct because runtimeconfig.json files are always next to the assembly. But in the ILStrip PR case, because the assembly when stripped moves to a different location, the old path is no longer reachable. Thus the old path needs to be retained, and used.