Use a custom runner in interpretExt and don't ignore TEST_ASSERT in dfsInstr

Description

When the debugger encounters a TEST_ASSERT instruction, its inner execution is not shown. This happens because interpretExt should take a custom runner instead of using runInstrNoGas so that the debugger can properly interpret its inner instructions.

Breakpoints cannot be set inside TEST_ASSERT because dfsInstr doesn't consider the inner instructions of TEST_ASSERT. This MR also fixes this.

Related issue(s)

This is a pre-requisite to solving morley-debugger#11 (closed)

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