scripts/: add script to check common page errors

[Managor]

This is a very crude run-and-done script collected from #17107

[sebastiaanspeck]

The build for this PR failed with the following error(s) at commit
17f0438556b4ff87c6cd3c0a5c14cdcf41a7bf1b:

In scripts/check-errors.sh line 9:
find . -type f -print0 | xargs -0 awk '{ q=gsub(/"/,"&"); if(q % 2 != 0) print FILENAME ": " $0 }'
                                      ^-- SC2016 (info): Expressions don't expand in single quotes, use double quotes for that.


In scripts/check-errors.sh line 17:
grep -r ?ref_type=heads
        ^-------------^ SC2062 (warning): Quote the grep pattern so the shell won't interpret it.
        ^-- SC2035 (info): Use ./*glob* or -- *glob* so names with dashes won't become options.


In scripts/check-errors.sh line 18:
grep -r ?tab=readme-ov-file
        ^-----------------^ SC2062 (warning): Quote the grep pattern so the shell won't interpret it.
        ^-- SC2035 (info): Use ./*glob* or -- *glob* so names with dashes won't become options.


In scripts/check-errors.sh line 19:
grep -r ?utm_source=chatgpt.com
        ^---------------------^ SC2062 (warning): Quote the grep pattern so the shell won't interpret it.
        ^-- SC2035 (info): Use ./*glob* or -- *glob* so names with dashes won't become options.


In scripts/check-errors.sh line 39:
grep -r ’
        ^-- SC1110 (warning): This is a unicode quote. Delete and retype it (or quote to make literal).


In scripts/check-errors.sh line 40:
grep -r ”
        ^-- SC1110 (warning): This is a unicode quote. Delete and retype it (or quote to make literal).


In scripts/check-errors.sh line 43:
grep -r "^-" | grep {{
                    ^-- SC1083 (warning): This { is literal. Check expression (missing ;/\n?) or quote it.
                     ^-- SC1083 (warning): This { is literal. Check expression (missing ;/\n?) or quote it.

For more information:
  https://www.shellcheck.net/wiki/SC1083 -- This { is literal. Check expressi...
  https://www.shellcheck.net/wiki/SC1110 -- This is a unicode quote. Delete a...
  https://www.shellcheck.net/wiki/SC2062 -- Quote the grep pattern so the she...

Please fix the error(s) and push again.

Is this fixable?

[Managor]

Not touching the last one as its purpose is to find unmatched "