Adds rmarkdown module (#944)

# Pull Request

<!--- Replace `#nnn` with your issue link for reference. -->

- Fixes insightsengineering/coredev-tasks#675

Thanks to @StefanThoma's for working on the first prototype

### Changes description

- Adds rmarkdown module
- Renders the output to module UI and to Reporter
- Source code is not verified as it adds a comment on how to render it
- Adds download button to get the original Rmd file
  - Option in module to enable or disable this functionality
- downloaded Rmd has module's data included (data pre-processing +
filter)
- Uses `extra_transform` parameter to add "generic decorators" to the
top of the UI
  - name is temporary
- [x] Ensure figures are displayed properly in reporter (PDF output)
- [x] Avoid encoding images to base64 (mayb keep it in raw or
equivalent)

### To discuss

- Should we render the `.R` to get all the R code from the report and
add it to the code of the `qenv`?
- [limitation] Use of `markdown` when rendering doesn't print title nor
author
  - Rendering it on the page breaks `teal`
- Wrapping in `iframe` doesn't extend full height and then creates
strange reports
- Should we use `transformers` to add extra input / data manipulation
- Or keep a parameters that allows to add transforms _(for example extra
inputs)_ to the module by the app developer

(topics below added from conversation with @gogonzo )

- should `teal_report` contain markdown elements?
- should `teal_data` evaluate `rmarkdown::render()` and include this to
`@code`
- should markdown be evaluated with `rmarkdown::render(envir = <qenv>)`
instead of `params = list()`?
  - visibility concern here on developing the Rmd

### App (same 2nd one in example, but with `download = TRUE`)

```r
pkgload::load_all("../teal.modules.general")

data <- teal_data()
data <- within(data, {
  CO2 <- CO2
  CO2[["primary_key"]] <- seq_len(nrow(CO2))
})
join_keys(data) <- join_keys(join_key("CO2", "CO2", "primary_key"))

static_decorator <- teal_transform_module(
  label = "N Cols selector",
  ui = function(id) {
    ns <- NS(id)
    tags$div(
      numericInput(ns("n_rows"), "Show n rows", value = 5, min = 0, max = 200, step = 5)
    )
  },
  server = function(id, data) {
    moduleServer(id, function(input, output, session) {
      reactive({
        req(data())
        within(data(), {
          n_rows <- n_rows_value
        }, n_rows_value = input$n_rows)
      })
    })
  }
)

app <- init(
  data = data,
  modules = modules(
    tm_rmarkdown(
      label = "RMarkdown Module",
      rmd_content = readLines(system.file(file.path("sample_files", "co2_example.Rmd"), package = "teal.modules.general")),
      allow_download = TRUE,
      extra_transform = list(static_decorator)
    )
  )
) |> shiny::runApp()
```

---------

Signed-off-by: André Veríssimo <[email protected]>
Co-authored-by: github-actions <41898282+github-actions[bot]@users.noreply.github.com>
Co-authored-by: Lluís Revilla <[email protected]>

Author: 3 people

DESCRIPTION

@@ -48,6 +48,7 @@ Imports:
     lattice (>= 0.18-4),
     lifecycle (>= 0.2.0),
     MASS (>= 7.3-60),
+    rmarkdown (>= 2.23),
     rtables (>= 0.6.11),
     scales (>= 1.3.0),
     shinyjs (>= 2.1.0),
@@ -73,7 +74,6 @@ Suggests:
     nestcolor (>= 0.1.0),
     pkgload,
     rlang (>= 1.0.0),
-    rmarkdown (>= 2.23),
     roxy.shinylive,
     rvest,
     shinytest2,

NAMESPACE

@@ -8,6 +8,8 @@ S3method(create_sparklines,default)
 S3method(create_sparklines,factor)
 S3method(create_sparklines,logical)
 S3method(create_sparklines,numeric)
+S3method(teal.reporter::to_rmd,markdown_internal)
+S3method(tools::toHTML,markdown_internal)
 export(add_facet_labels)
 export(get_scatterplotmatrix_stats)
 export(tm_a_pca)
@@ -23,6 +25,7 @@ export(tm_g_scatterplot)
 export(tm_g_scatterplotmatrix)
 export(tm_missing_data)
 export(tm_outliers)
+export(tm_rmarkdown)
 export(tm_t_crosstable)
 export(tm_variable_browser)
 import(ggplot2)