Ignore custom VTIMEZONEs that can't be properly handled by ical4j (#96)

* Improve build speed by enabling gradle configuration cache

* Added rules for fixing Dublin timezone

Signed-off-by: Arnau Mora <arnyminer.z@gmail.com>

* Added rules for fixing Dublin timezone

Signed-off-by: Arnau Mora <arnyminer.z@gmail.com>

* Added test for Dublin preprocessing

Signed-off-by: Arnau Mora <arnyminer.z@gmail.com>

* Applying rules for properties and components

Signed-off-by: Arnau Mora <arnyminer.z@gmail.com>

* Added test for `testTzDublin_external`

Signed-off-by: Arnau Mora <arnyminer.z@gmail.com>

* Changed rule replacement method

Signed-off-by: Arnau Mora <arnyminer.z@gmail.com>

* Use ValidatingTimeZoneRegistry to ignore time zone updates that can't be handled properly by ical4j

* Rollback

Signed-off-by: Arnau Mora Gras <arnyminerz@proton.me>

* Enable ical4j flag to support timezone definitions with negative DST

* Optimize imports

* Remove duplicate test

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Signed-off-by: Arnau Mora <arnyminer.z@gmail.com>
Signed-off-by: Arnau Mora Gras <arnyminerz@proton.me>
Co-authored-by: Arnau Mora <arnyminerz@proton.me>