New+: Fixed issue with files and folders containing only numbers

[cgaarden]

Summary of the Pull Request

Supersedes #41465

1. Fix for where template file or folder only contained numbers
2. Fix for where hidden files are shown in the list of templates

PR Checklist

• Closes: New+ #36216
• Communication: I've discussed this with core contributors already. If the work hasn't been agreed, this work might be rejected
• [n/a] Tests: Added/updated and all pass
• [n/a] Localization: All end-user-facing strings can be localized
• [n/a] Dev docs: Added/updated
• [n/a] New binaries: Added on the required places
  • [n/a] JSON for signing for new binaries
  • [n/a] WXS for installer for new binaries and localization folder
  • [n/a] YML for CI pipeline for new test projects
  • [n/a] YML for signed pipeline
• [n/a] Documentation updated: If checked, please file a pull request on our docs repo and link it here: #xxx

Detailed Description of the Pull Request / Additional comments

1. Fix for where template file or folder only contained numbers
   // Filename cases to support
   // type | filename | result
   // [file] | 01. First entry.txt | First entry.txt
   // [folder] | 02. Second entry | Second entry
   // [folder] | 03 Third entry | Third entry
   // [file] | 04 Fourth entry.txt | Fourth entry.txt
   // [file] | 05.Fifth entry.txt | Fifth entry.txt
   // [folder] | 001231 | 001231
   // [file] | 001231.txt | 001231.txt
   // [file] | 13. 0123456789012345.txt | 0123456789012345.txt

2. Fix for where hidden files are shown in the list of templates
   Instead of excluding based on filename (desktop.ini) exclude based on hidden and system attribute being set

Validation Steps Performed

Before fix

Notice
1) Folders with numbers only aren't displayed on the context menu
2) Files with extension with numbers only show extension on the context menu
3) Some hidden files are shown

After fixes

Scenario 1

New+ Setting: Hide leading digits…: Yes
New+ Setting: Hide file extension: Yes
New+ Setting: Replace variables: No

Scenario 2

New+ Setting: Hide leading digits…: No
New+ Setting: Hide file extension: No
New+ Setting: Replace variables: No

Scenario 3

New+ Setting: Hide leading digits…: Yes
New+ Setting: Hide file extension: Yes
New+ Setting: Replace variables: Yes

[cgaarden]

Hi @niels9001, here's the PR for the folders with numbers only in them + various permutations. I've also ensured that hidden and systems files are excluded from the list of templates.