fix: only resolve bioc repositories when a project includes a bioc-sourced package

[joshyam-k]

Fixes #1337

Instead of eagerly evaluating Bioconductor repositories, only do so when the project actually contains a Bioconductor-sourced package. This PR also creates a isBiocPackage helper that gets reused across R/bundlePackageRenv.R

Following the reproduction steps in #1337:

Before

> rsconnect::writeManifest(appDir = "proj")
ℹ Capturing R dependencies from renv.lock
  Error: invalid version specification 'unknown version: Bioconductor version cannot be validated;
      no internet connection?
      See #troubleshooting section in vignette'

After

> options(repos = c(CRAN = "https://cloud.r-project.org"))
> rsconnect::writeManifest(appDir = "proj")
ℹ Capturing R dependencies from renv.lock
✔ Found 2 dependencies

[joshyam-k]

sorry- I hate when github makes a diff look confusing like this. We're just wrapping the lines that were previously 62-64 and 66-67 with a new hasBiocPackage(...) gate.

[jonkeane]

This looks good to me, I would love to get @karawoo 's take as well, but tests pass and the code looks right.