scripts: Address shellcheck issues

Report issues by shell files with:

    git ls-files '*.sh' | xargs shellcheck --exclude=SC2162

Address the following:

- SC1087: Use braces when expanding arrays
- SC1091: Not following
- SC2004: `$`/`${}` is unnecessary on arithmetic variables
- SC2024: `sudo` doesn't affect redirects
- SC2034: foo appears unused. Verify it or export it
- SC2086: Double quote to prevent globbing and word splitting
- SC2087: Quote `EOF`
- SC2115: Use `"${var:?}"` to ensure this never expands to `/*`
- SC2148: Add a shebang

Addresses (at least partially) some POSIX/dash issues:

- SC2113: `function` keyword is non-standard
- SC3010: In POSIX sh, `[[` `]]` is undefined
- SC3014: In POSIX sh, `==` in place of `=` is undefined
- SC3020: In POSIX sh, `&>` is undefined
- SC3046: In POSIX sh, `source` in place of `.` is undefined

Does not address:

- SC2162: `read` without `-r` will mangle backslashes
- Any other POSIX/dash-specific issues

Signed-off-by: Tim Crawford <tcrawford@system76.com>

scripts/remotes.sh

@@ -8,7 +8,7 @@ REMOTES=(
 
 set -e
 
-function git_remote {
+git_remote() {
     echo -e "\x1B[1m$1\x1B[0m"
     pushd "$1" > /dev/null
     if git remote | grep "^$2\$"
@@ -23,5 +23,5 @@ function git_remote {
 
 for remote in "${REMOTES[@]}"
 do
-    git_remote $remote
+    git_remote "$remote"
 done