* bump_dependencies.md: add nim-results dependency
* change imports stew/results to results
* switching to Nim 2.0.8
* waku.nimble: reflect the requirement nim 1.6.0 to 2.0.8
Adding --mm:refc as nim 2.0 enables a new garbage collector that we're
not yet ready to support
* adapt waku code to Nim 2.0
* gcsafe adaptations because Nim 2.0 is more strict
* message.nim: set max message size to 150KiB according to spec
Using KiB instead of KB because that seems more aligned with
the actual default defined in nim-libp2p (1024 * 1024)
Spec details: https://rfc.vac.dev/spec/64/#message-size
* test_protocol.nim: align test to current WakuMessage limit
* test_waku_client.nim: adapt test to MaxWakuMessageSize change
* make maxMessageSize configurable for wakunode2
* wakunode2 app now accepts max-num-bytes-msg-size with KiB, KB, or B units
* testlib/wakunode.nim: set maxMessageSize: "1024 KiB"
* test_waku_client.nim: remove duplicate check in "Valid Payload Sizes"
* set DefaultMaxWakuMessageSizeStr as the only source of truth
* external_config.nim: rename max-num-bytes-msg-size -> max-msg-size
Ivan FB