fix: gracefully parse non-standard trusted certificates

[st3iny]

• Resolves: none

Summary

The format -----BEGIN TRUSTED CERTIFICATE----- is non-standard and only used by OpenSSL. However, they can still be parsed by PHP through OpenSSL if the separator strings are simply replaced.

I also added a simple unit test with a sample certificate.

Checklist

• Code is properly formatted
• Sign-off message is added to all commits
• Tests (unit, integration, api and/or acceptance) are included
• Screenshots before/after for front-end changes
• Documentation (manuals or wiki) has been updated or is not required
• Backports requested where applicable (ex: critical bugfixes)

[szaimen]

LGTM and new unit test seem to pass 😎

[szaimen]

/backport to stable30

[szaimen]

/backport to stable29

[provokateurin]

/backport to stable28

[backportbot]

The backport to stable29 failed. Please do this backport manually.

# Switch to the target branch and update it
git checkout stable29
git pull origin stable29

# Create the new backport branch
git checkout -b backport/48307/stable29

# Cherry pick the change from the commit sha1 of the change against the default branch
# This might cause conflicts, resolve them
git cherry-pick 19ad1357

# Push the cherry pick commit to the remote repository and open a pull request
git push origin backport/48307/stable29

Error: No changes found in backport branch

---

Learn more about backports at https://docs.nextcloud.com/server/stable/go.php?to=developer-backports.

[backportbot]

The backport to stable28 failed. Please do this backport manually.

# Switch to the target branch and update it
git checkout stable28
git pull origin stable28

# Create the new backport branch
git checkout -b backport/48307/stable28

# Cherry pick the change from the commit sha1 of the change against the default branch
# This might cause conflicts, resolve them
git cherry-pick 19ad1357

# Push the cherry pick commit to the remote repository and open a pull request
git push origin backport/48307/stable28

Error: No changes found in backport branch

---

Learn more about backports at https://docs.nextcloud.com/server/stable/go.php?to=developer-backports.

[st3iny]

/backport to stable28

[st3iny]

/backport to stable29

[backportbot]

The backport to stable29 failed. Please do this backport manually.

# Switch to the target branch and update it
git checkout stable29
git pull origin stable29

# Create the new backport branch
git checkout -b backport/48307/stable29

# Cherry pick the change from the commit sha1 of the change against the default branch
# This might cause conflicts, resolve them
git cherry-pick 19ad1357

# Push the cherry pick commit to the remote repository and open a pull request
git push origin backport/48307/stable29

Error: No changes found in backport branch

---

Learn more about backports at https://docs.nextcloud.com/server/stable/go.php?to=developer-backports.

[backportbot]

The backport to stable28 failed. Please do this backport manually.

# Switch to the target branch and update it
git checkout stable28
git pull origin stable28

# Create the new backport branch
git checkout -b backport/48307/stable28

# Cherry pick the change from the commit sha1 of the change against the default branch
# This might cause conflicts, resolve them
git cherry-pick 19ad1357

# Push the cherry pick commit to the remote repository and open a pull request
git push origin backport/48307/stable28

Error: No changes found in backport branch

---

Learn more about backports at https://docs.nextcloud.com/server/stable/go.php?to=developer-backports.