scripts: Rspamd stabilization pt. 2 (#3282)

* move modules adjustment file to new location

Because we link `/tmp/docker-mailserver/rspamd/override.d` to
`/etc/rspamd/override.d`, I think it makes sense to move the modules
adjustment file into `/tmp/docker-mailserver/rspamd/` as well.

I write the code in a way that it is backwards compatible for now, so
this is NOT a breaking change.

* minor improvement to `__rspamd__handle_user_modules_adjustments`

The expansion of `ARGUMENT3` is now done in a way that only adds the
whitespace in case the variable is set and not null.

* move test file structure to respect latest changes

Because we're now linking `rspamd/override.d/`, we can simplify the
setup a bit. But this requires a change in directory structure.

The current Rspamd test will be renamed to `rspamd_full.bats`, because I
plan on adding more tests in different files for different feature sets.
This is done to make this feature well-tested!

* improved and added tests to Rspamd-full

FYI: The line

```bats
_run_in_container grep 'sieve_global_extensions.*\+vnd\.dovecot\.pipe'
"${SIEVE_CONFIG_FILE}"
```

was testing a condition that should actually not be met, but when I
started working on this feature, I thought this was the correct
configuration. Adding the `assert_success` statements revealed this
wrong line.

I also added tests to check whether `override.d` is linked correctly.

* renamed: `rspamd.bats` => `rspamd_full.bats`

* added new tests for incomplete Rspamd feature set

We now test that warnings are emitted & features are disabled correctly.

* update documentation

test/config/rspamd_full/rspamd/custom-commands.conf

@@ -0,0 +1,42 @@
+# This is suboptimal, but not strictly required either: we do not
+# need the DKIM signing & RBL functionality (which is most likely
+# not set up anyway or it fails (in case of querying DNSBLs with
+# public resolvers)). Hence, we disable it. It is suboptimal
+# since we are testing the functionality of whether disabling
+# a module works at the same time..
+#
+# When testing on ARM64, this is required at the moment due to
+# strange behavior in Rspamd v3.2 (segmentation faults) when DKIM
+# keys are not provided (notes were added to the docs).
+disable-module dkim_signing
+disable-module rbl
+
+# check whether disabling a module works and whether it
+# really overwrites options that came before
+set-option-for-module testmodule1 someoption somevalue
+disable-module testmodule1
+
+# enabling a module and setting some options for it
+enable-module testmodule2
+set-option-for-module testmodule2 someoption somevalue
+set-option-for-module testmodule2 anotheroption whatAvaLue
+
+# overwriting an option (probably unwanted, we emit a warning)
+set-option-for-module testmodule3 someoption somevalue1
+set-option-for-module testmodule3 someoption somevalue2
+
+# check whether adding a line works even with special characters in it
+add-line testmodule4.something some very long line with "weird $charact"ers
+add-line testmodule4.something and! ano. ther &line
+add-line testmodule4.something # some comment
+
+# check whether spaces in front are handles fine, for nested options
+set-option-for-module testmodule_complicated anOption anotherValue
+
+# check whether controller and proxy options are set/overwritten correctly
+set-option-for-controller someOption someValue42
+set-option-for-proxy abcdefg71 RaNDom
+set-option-for-proxy abcdefg71 RAAAANdooM
+
+# check whether setting basic options works (and whether spaces in values work)
+set-common-option OhMy "PraiseBeLinters !"

test/config/rspamd_full/rspamd/override.d/testmodule_complicated.conf

@@ -0,0 +1,3 @@
+complicated {
+    anOption = someValue;
+}