Fix code scanning alert no. 6: Incomplete string escaping or encoding

[tdonohue]

(NOTE: This PR was autogenerated by Copilot Autofix. I did not write the text below, nor the code changes in this PR)

Fixes https://github.com/DSpace/dspace-angular/security/code-scanning/6

To fix the problem, we need to ensure that backslashes in the inputKey are properly escaped before constructing the regular expression. This can be done by adding an additional replace call to escape backslashes. The best way to fix this without changing existing functionality is to modify the line where the regular expression is constructed.

• Modify the line where inputKeyRegex is defined to include an additional replace call for escaping backslashes.
• Ensure that the replace method uses a regular expression with the global flag to replace all occurrences of backslashes.

Suggested fixes powered by Copilot Autofix. Review carefully before merging.

[tdonohue]

👍 As noted above, I didn't write this code. It was written by GitHub AutoPilot. However, I think this code looks reasonable...it just adds a new .replace() to handle backslashes properly. This also passes our detailed automated tests in metadata.utils.spec.ts.

(Technically, I don't think it should be possible to pass backslashes into this regex. But, it's better to be safe. So, I think this looks reasonable.)

[tdonohue]

👍 Tested locally and found no changes in behavior. This is primarily used in import (via external sources) and object display. Tested those and everything seems to work well.

[dspace-bot]

Successfully created backport PR for dspace-7_x:

• [Port dspace-7_x] Fix code scanning alert no. 6: Incomplete string escaping or encoding #3545

[dspace-bot]

Successfully created backport PR for dspace-8_x:

• [Port dspace-8_x] Fix code scanning alert no. 6: Incomplete string escaping or encoding #3546