arrow

ARROW-5492: [R] Add "col_select" argument to read_* functions to read subset of columns

``` r
library(arrow, warn.conflicts = FALSE)
library(tibble)

tf <- tempfile()
write.csv(iris, tf, row.names = FALSE, quote = FALSE)

read_csv_arrow(tf, col_select = starts_with("Sepal"))
#> # A tibble: 150 x 2
#>    Sepal.Length Sepal.Width
#>           <dbl>       <dbl>
#>  1          5.1         3.5
#>  2          4.9         3
#>  3          4.7         3.2
#>  4          4.6         3.1
#>  5          5           3.6
#>  6          5.4         3.9
#>  7          4.6         3.4
#>  8          5           3.4
#>  9          4.4         2.9
#> 10          4.9         3.1
#> # … with 140 more rows

tf <- tempfile()
write_feather(iris, tf)
read_feather(tf, col_select = contains("."))
#> # A tibble: 150 x 4
#>    Sepal.Length Sepal.Width Petal.Length Petal.Width
#>           <dbl>       <dbl>        <dbl>       <dbl>
#>  1          5.1         3.5          1.4         0.2
#>  2          4.9         3            1.4         0.2
#>  3          4.7         3.2          1.3         0.2
#>  4          4.6         3.1          1.5         0.2
#>  5          5           3.6          1.4         0.2
#>  6          5.4         3.9          1.7         0.4
#>  7          4.6         3.4          1.4         0.3
#>  8          5           3.4          1.5         0.2
#>  9          4.4         2.9          1.4         0.2
#> 10          4.9         3.1          1.5         0.1
#> # … with 140 more rows
```

<sup>Created on 2019-06-20 by the [reprex package](https://reprex.tidyverse.org) (v0.3.0.9000)</sup>

Author: Romain Francois <romain@rstudio.com>
Author: Romain François <romain@rstudio.com>

Closes #4627 from romainfrancois/ARROW-5492/tidyselect and squashes the following commits:

fe5906ceb <Romain François> Merge branch 'master' into ARROW-5492/tidyselect
89bcfdd11 <Romain Francois> always mmap
48fc793cc <Romain Francois> remmove ARROW_R_WITH_PARQUET
e7403c533 <Romain Francois> use remotes::install_github() instead of pak::pkg_install()
b73be3651 <Romain Francois> merge hickup
1e40a0da0 <Romain Francois> read_json_arrow(col_select=)
e112ff8c5 <Romain Francois> support for col_select=<tidy selection> in read_parquet()
21561b17b <Romain Francois> FileReader$GetSchema()
f6d824cf7 <Romain Francois> s/ParquetFileReader/FileReader/
f5bb537b0 <Romain Francois> expose parquet::arrow::ArrowReaderProperties
512579e06 <Romain Francois> expose ParquetFileReader at the R side
c44b9cb98 <Romain Francois> more read_csv_arrow(col_select=) tests
4d5515f8a <Romain Francois> read_csv_arrow(col_select=, as_tibble=)
07bcddaf6 <Romain Francois> Table$select(<tidy selection>)
826cd3aab <Romain Francois> tests for read_feather(col_select=<tidyselect helper>)
54b179fcf <Romain Francois> re exporting tidyselect helpers for convenience
e31098a4a <Romain Francois> read_feather(col_select=) using tidy selection, as in vroom::vroom