commit log keystore _isSpecialKey returns incorrect result for public keys

[murali-shris]

Describe the bug

bool _isSpecialKey(String atKey) {
return atKey.contains(AtConstants.atEncryptionSharedKey) ||
atKey.startsWith('public:') ||
atKey.contains(AtConstants.atPkamSignature) ||
atKey.contains(AtConstants.atSigningPrivateKey);
}

should be public:publickey.

Steps to reproduce

```
test('test to verify last committed sequenceNumber with regex', () async {
    var commitLogInstance =
        await (AtCommitLogManagerImpl.getInstance().getCommitLog('@alice'));
    var commit = await commitLogInstance?.commit(
        'public:location_1.wavi@alice', CommitOp.UPDATE);
    await commitLogInstance?.commit(
        'public:phone.buzz@alice', CommitOp.UPDATE);
    await commitLogInstance?.commit(
        'public:location_2.wavi@alice', CommitOp.UPDATE);
    await commitLogInstance?.commit(
        'public:email.buzz@alice', CommitOp.UPDATE);
    expect(await commitLogInstance
        ?.lastCommittedSequenceNumberWithRegex('buzz'), 3);
    expect(await commitLogInstance
        ?.lastCommittedSequenceNumberWithRegex('wavi'), 2);
  });
  ```
  this unit test fails

Expected behavior

unit test should pass

Screenshots

No response

Smartphones

No response

Were you using an atApplication when the bug was found?

No response

Additional context

No response

[murali-shris]

#2115 (comment)
Testing these changes

• replaced the check atKey.contains(AtConstants.atEncryptionSharedKey) with checks suggested in the PR review comment
• removed the checks for AtConstants.atPkamSignature, AtConstants.atSigningPrivateKey in _specialKey