checkAppLayout() fails when app.R is present even if app.R not included in appFiles

[rundel]

This was mostly an accidental edge case but when working in a directory with multiple single-file Shiny apps, one of which happened to be named app.R, it was no longer possible to deploy the other apps even when app.R was not selected as part of the deployment.

This occurs both with the RStudio gui or with the direct package interface:

rsconnect::deployApp(appFiles = "shiny.R", appPrimaryDoc = "shiny.R")
## ── Preparing for deployment ─────────────────────────────
## ✔ Deploying "shiny" to "server: rstudio02-metaproxy.production05.posit.academy / username: [email protected]"
## Error in `checkAppLayout()`:
## ! Project must not contain both app.R and a single-file Shiny app.
## Run `rlang::last_trace()` to see where the error occurred.

What I was trying to do is clearly not advisable but still seems undesirable that it should trigger an error and prevent deployment without renaming or moving files.

[aronatkins]

Notes:

• checkAppLayout() considers all files in the appDir root; it does not use appFiles.
• Many of the layout checks were removed in enforce fewer layout restrictions #1003