Add devmode() features

[schloerke]

Added:

• devmode(enable, verbose)
• in_devmode()
• with_devmode(devmode, code)
• devmode_inform(message, .frequency = "regularly", .frequency_id = message, ...)
• register_devmode_option(option, message, on)
• get_devmode_option(option, default = NULL, on = waiver(), message = waiver())
• These devmode options:

register_devmode_option(
  "shiny.autoreload",
  "Turning on shiny autoreload. To disable, call `options(shiny.autoreload = FALSE)`",
  TRUE
)

register_devmode_option(
  "shiny.minified",
  "Using full shiny javascript file. To use the minified version, call `options(shiny.minified = TRUE)`",
  FALSE
)

register_devmode_option(
  "shiny.fullstacktrace",
  "Turning on full stack trace. To disable, call `options(shiny.fullstacktrace = FALSE)",
  TRUE
)

Other updates:

• Removed ./R/htmltools.R as it is covered in ./R/reexports.R
• Consolidated all imports to ./R/shiny-package.R
• Soft deprecate shinyUI and shinyServer
• Add lifecycle svgs to use in macros docs
• Provide shiny deprecated messages using rlang::inform()
• Use lifecycle::deprecated()
• Import rlang::is_false()
• Better error messaging for failing template tests

[schloerke]

(current windows failure is unrelated to changes made in PR)

[wch]

For dev_mode()

• Maybe there's a better name than dev_mode()? Also, maybe listen to an option like options(shiny.devmode=TRUE), so that people can set it in their .Rprofile without causing shiny to load?
• Display warnings about upcoming deprecations (like reactive with env and quoted)
• Disable various forms of caching, in sass and bslib
• Give hints about cache keys (not yet), and print out if missing one or more
• Deprecate renderDataTable - use DT instead
• shinyUI(), shinyServer() functions - can’t ever get rid of these, but we can message in dev mode
  • Call these functions superseded, in tidyverse terminology.
• Automatically turn on shiny.minified = FALSE

[schloerke]

macOS failures are due to rstudio/webdriver#59 (existing before PR). Merging