lib-sieve: sieve-result - Fix panic occurring upon temp fail after committed keep-equivalent action.

The determination of whether a keep-equivalent action was already executed is
performed in sieve_result_implicit_keep_execute(), which can also be called from
sieve_result_implicit_keep_finalize(). But there, the keep-equivalent status was
checked before any call to sieve_result_implicit_keep_execute(), which would
thus yield the wrong result.

This change also makes the associated debug message more specific (otherwise two
identical debug messages are logged) and an assert is added that makes sure the
keep-equivalent action is actually finalized when the implicit keep was supposed
to be finalized.

Panic was:

Panic: file sieve-result.c: line 1706 (sieve_result_implicit_keep_finalize): assertion failed: (aexec_keep->state == SIEVE_ACTION_EXECUTION_STATE_EXECUTED)

lib-sieve: sieve-result - Indicate in sieve_result_transaction_finalize() debug message whether actions were committed.

lib-sieve: sieve-result - Indicate in sieve_result_transaction_execute() debug message whether actions were executed.

lib-sieve: sieve-result - Assert that implicit keep is executed in sieve_result_implicit_keep_finalize().

lib-sieve: sieve-result - Fix resource leak occurring when implicit keep is executed before temporary failure at commit.

In the commit phase the implicit keep was never finalized, meaning that it was
not rolled back and thus not cleaned up properly. This leads to a memory leak
and a mailbox reference leak. This in turn causes an assert crash at the end
of delivery when the mail user is destroyed.

It will be executed in the commit phase if necessary; don't do it early; it will
only be rolled back.

lib-sieve: sieve-result - Move temp failure status checks into sieve_result_implicit_keep_finalize().

lib-sieve: sieve-result - Move temp failure status checks into sieve_result_implicit_keep_execute().

lib-sieve: sieve-result - Fix omission of action finalization happening upon result execution failure.

This occurred because the code that checks for a deferred keep action in
sieve_result_implicit_keep_execute() could end up "finding" an action that
wasn't actually a deferred keep. That action was then erroneously promoted to
the FINALIZED state, which meant that commit/rollback was never executed.

This had no real purpose and could cause NULL pointer dereference.

Found by Clang scan-build.

This is currently not used, but prevents mishaps once such code is written.

This is not currently used, but the absence of the call could cause memory leaks
in the future.

Call sieve_action_execution_pre() just before the first action activity and
always call sieve_action_execution_post() at the end of each action activity.
This makes things clearer and it makes the next commit easier.

lib-sieve: sieve-result - Remove code duplication between implicit keep and normal action execution.

Preparation for next commit.

Before, actions were executed and committed in full after each script in a
sequence. With this change, actions can still be rolled back until the end of
all Sieve script and action execution.

The committed flag is set when at least one action was committed successfully.
The existing executed flag is repurposed to signal successful execution of at
least one action. These flags are now also properly managed for the keep action.

Allows doing the check in the action finalization function.

It is no longer used.

Adds status parameter to sieve_result_execute().

Makes sure it is consistent for a later commit when action exection is more fragmented.