Enforce consistent and correct toml formatting (#2518)

Using taplo, fixes all our broken and inconsistent toml formatting and
adds CI to keep them tidy.

If people want we can customise the format rules as described here
https://taplo.tamasfe.dev/configuration/formatter-options.html

@ggwpez, I suggest zepter is used only for checking features are
propagated, and leave formatting for taplo to avoid duplicate work and
conflicts.

TODO
- [x] Use `exclude = [...]` syntax in taplo file to ignore zombienet
tests instead of deleting the dir

---------

Signed-off-by: Oliver Tale-Yazdi <oliver.tale-yazdi@parity.io>
Co-authored-by: Oliver Tale-Yazdi <oliver.tale-yazdi@parity.io>
Co-authored-by: Bastian Köcher <git@kchr.de>

.gitlab/pipeline/check.yml

@@ -90,6 +90,16 @@ check-rust-feature-propagation:
     - cargo install --locked --version 0.13.3 -q -f zepter && zepter --version
     - zepter run check
 
+check-toml-format:
+  stage: check
+  extends:
+    - .kubernetes-env
+    - .common-refs
+  script:
+    - cargo install taplo-cli --locked --version 0.8.1
+    - taplo format --check --config .config/taplo.toml
+    - echo "Please run `taplo format --config .config/taplo.toml` to fix any toml formatting issues"
+
 # More info can be found here: https://github.com/paritytech/polkadot/pull/5865
 .check-runtime-migration:
   stage: check

.gitlab/spellcheck.toml

@@ -8,20 +8,20 @@ use_builtin = true
 [hunspell.quirks]
 # He tagged it as 'TheGreatestOfAllTimes'
 transform_regex = [
-# `Type`'s
+	# `Type`'s
 	"^'([^\\s])'$",
-# 5x
-# 10.7%
+	# 5x
+	# 10.7%
 	"^[0-9_]+(?:\\.[0-9]*)?(x|%)$",
-# Transforms'
+	# Transforms'
 	"^(.*)'$",
-# backslashes
-	"^\\+$",
+	# backslashes
 	"^[0-9]*+k|MB|Mb|ms|Mbit|nd|th|rd$",
-# single char `=` `>` `%` ..
+	"^\\+$",
+	# single char `=` `>` `%` ..
 	"^=|>|<|%$",
-# 22_100
-	"^(?:[0-9]+_)+[0-9]+$"
+	# 22_100
+	"^(?:[0-9]+_)+[0-9]+$",
 ]
 allow_concatenation = true
 allow_dashes = true