tests: Revise LDAP config + setup (#3514)

* chore: Use  white-space in query filters to improve readability

* tests: LDAP ENV query filters documented

- These filters remain roughly the same as they were before. The conditions are the same, but restructured to make the complimentary constraints more separated from the actual target attribtues.
- The DOMAIN query additionally includes the `mailAlias` from `PostfixBookMailAccount` class as well.
- Heavy inline documentation breaking down how the filters work for any maintainer to reference. This will likely be migrated after revision into our user docs for LDAP. Some quirks have also been noted with advice for future changes.

* tests: LDAP - Support test-case specific containers

A bit more complicated than other test files due to the larger ENV config array that most containers may need to share.

Example introduced with the test-case checking custom config file support.

* tests: Adjust LDAP test configs

- Paths for `.ldif` files used with volumes shortened
- Postfix LDAP `.cf` files adjusted to conventions used in LDAP tests.

test/config/ldap/openldap/ldifs/01_mail-tree.ldif

@@ -0,0 +1,16 @@
+# The root object of the tree, all entries will branch off this one:
+dn: dc=example,dc=test
+# DN is formed from `example.test` DNS labels:
+# NOTE: This is just a common convention (not dependent on hostname or any external config)
+objectClass: dcObject
+# Must reference left most component:
+dc: example
+# It's required to use an `objectClass` that implements a "Structural Class":
+objectClass: organization
+# Value is purely descriptive, not important to tests:
+o: DMS Test
+
+# User accounts will belong to this subtree:
+dn: ou=users,dc=example,dc=test
+objectClass: organizationalUnit
+ou: users

test/config/ldap/openldap/ldifs/02_user-email.ldif

@@ -0,0 +1,21 @@
+# NOTE: A standard user account to test against
+dn: uid=some.user,ou=users,dc=example,dc=test
+objectClass: inetOrgPerson
+objectClass: PostfixBookMailAccount
+cn: Some User
+givenName: Some
+surname: User
+userID: some.user
+# Password is: secret
+userPassword: {SSHA}eLtqGpid+hkSVhxvsdTPztv4uapRofGx
+mail: some.user@localhost.localdomain
+# postfix-book.schema:
+mailAlias: postmaster@localhost.localdomain
+mailGroupMember: employees@localhost.localdomain
+mailHomeDirectory: /var/mail/localhost.localdomain/some.user/
+mailStorageDirectory: maildir:/var/mail/localhost.localdomain/some.user/
+# postfix-book.schema generic options:
+mailEnabled: TRUE
+mailUidNumber: 5000
+mailGidNumber: 5000
+mailQuota: 10240

test/config/ldap/openldap/ldifs/03_user-email-other-primary-domain.ldif

@@ -0,0 +1,22 @@
+# NOTE: This user differs via the domain-part of their mail address
+# They also have their mail directory attributes using the primary domain, not their domain-part
+dn: uid=some.other.user,ou=users,dc=example,dc=test
+objectClass: inetOrgPerson
+objectClass: PostfixBookMailAccount
+cn: Some Other User
+givenName: Some
+surname: Other User
+userID: some.other.user
+# Password is: secret
+userPassword: {SSHA}eLtqGpid+hkSVhxvsdTPztv4uapRofGx
+mail: some.other.user@localhost.otherdomain
+# postfix-book.schema:
+mailAlias: postmaster@localhost.otherdomain
+mailGroupMember: employees@localhost.otherdomain
+mailHomeDirectory: /var/mail/localhost.localdomain/some.other.user/
+mailStorageDirectory: maildir:/var/mail/localhost.localdomain/some.other.user/
+# postfix-book.schema generic options:
+mailEnabled: TRUE
+mailUidNumber: 5000
+mailGidNumber: 5000
+mailQuota: 10240

test/config/ldap/openldap/ldifs/04_user-email-different-uid.ldif

@@ -0,0 +1,20 @@
+# NOTE: This user differs by local-part of mail address not matching their uniqueIdentifier attribute
+# They also do not have any alias or groups configured
+dn: uid=some.user.id,ou=users,dc=example,dc=test
+objectClass: inetOrgPerson
+objectClass: PostfixBookMailAccount
+cn: Some User
+givenName: Some
+surname: User
+userID: some.user.id
+# Password is: secret
+userPassword: {SSHA}eLtqGpid+hkSVhxvsdTPztv4uapRofGx
+mail: some.user.email@localhost.localdomain
+# postfix-book.schema:
+mailHomeDirectory: /var/mail/localhost.localdomain/some.user.id/
+mailStorageDirectory: maildir:/var/mail/localhost.localdomain/some.user.id/
+# postfix-book.schema generic options:
+mailEnabled: TRUE
+mailUidNumber: 5000
+mailGidNumber: 5000
+mailQuota: 10240