[KS-182] keystone: Refactor write_capability + add ChainWriter

.changeset/large-plants-count.md

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+---
+"chainlink": minor
+---
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+#internal Added a configuration option to chain writer to set the tx send strategy.

.changeset/real-tools-tap.md

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+---
+"chainlink": minor
+---
+
+#internal added tests for Chainwriter

.changeset/tricky-flowers-exist.md

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+---
+"chainlink": minor
+---
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+#added A ChainWriter implementation in the EVM relay.