compiler: Rejects RULES whose LHS immediately fails to type-check

This is a bug fix for #24026 (closed): RULES that do not type check causing the compiler to crash when -fdefer-type-errors is used. There is a detailed conversation on #24026 (closed), but to summarize there are two changes.

• A bug fix on decomposeRuleLhs that fix the fact that coercion variables where being ignored on decomposition.
• A design choice to ignore rules that don't type-check early on. On normal programs built with no special flags (see T24026b), type-checking fails with the expected error. If for any reason, for example -fdefer-type-errors is used, and the compilation continues, rules that outright don't type check due to LHS failures will be ignored further, the user sees a warning, and GHC does not crash.

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