GH-50824: [R] Fix shellcheck errors in the r/tools/download_dependencies_R.sh

[hiroyuki-sato]

Rationale for this change

This is the sub issue #44748.

• SC2086: Double quote to prevent globbing and word splitting.

shellcheck r/tools/download_dependencies_R.sh

In r/tools/download_dependencies_R.sh line 48:
  echo 'download.file("'${url}'", "'${out}'", quiet = TRUE)'
                        ^----^ SC2086 (info): Double quote to prevent globbing and word splitting.
                                    ^----^ SC2086 (info): Double quote to prevent globbing and word splitting.

Did you mean:
  echo 'download.file("'"${url}"'", "'"${out}"'", quiet = TRUE)'


In r/tools/download_dependencies_R.sh line 59:
  source ${SOURCE_DIR}/cpp/thirdparty/versions.txt
         ^-----------^ SC2086 (info): Double quote to prevent globbing and word splitting.

Did you mean:
  source "${SOURCE_DIR}"/cpp/thirdparty/versions.txt

For more information:
  https://www.shellcheck.net/wiki/SC2086 -- Double quote to prevent globbing ...

What changes are included in this PR?

• SC2086: Quote variable

Are these changes tested?

Yes.

Are there any user-facing changes?

No.

• GitHub Issue: [R] Fix shellcheck errors in the r/tools/download_dependencies_R.sh #50824

[github-actions]

⚠️ GitHub issue #50824 has been automatically assigned in GitHub to PR creator.

[hiroyuki-sato]

@github-actions crossbow submit test-r-offline-maximal

[github-actions]

Revision: a58b6c2

Submitted crossbow builds: ursacomputing/crossbow @ actions-62f8e0cdba

Task	Status
test-r-offline-maximal