newly generated JS repo flavor packages fail to build

[jeremymeng]

issue:

The code generator should also generate the new ./config and relevant config files but didn't

analysis

SDK Validation - JS is broken for all TypeSpec-based PRs in azure-rest-api-specs

Error:
 

[warp] Invalid config in warp.config.yml: target "browser" references tsconfig 
"./config/tsconfig.src.browser.json" which does not exist at 
.../azure-sdk-for-js/sdk/cognitiveservices/arm-cognitiveservices/config/tsconfig.src.browser.json
 

Root cause:
 

The JS emitter @azure-tools/typespec-ts version 0.53.0/0.53.1 (published today, May 14) generates warp.config.yml with
new-style local paths (./config/tsconfig.src.browser.json) per #3938 (
#3938) ("feat: migrate generated configs to eng/tsconfigs pattern").
However, the emitter is generating warp.config.yml with these new paths without also generating the config/ directory
containing the thin tsconfig files that extend from eng/tsconfigs/.

fix

We should include the config/tsconfig.src.*.json files that are referenced in warp.config.yml under targets section. They should be similar to files under https://github.com/Azure/azure-sdk-for-js/tree/e27a67644732133358031641557731736e0b4f4b/sdk/core/core-rest-pipeline/config