[#711] Reduce the number of unsafe functions at the call site

Description

Some constructors/converters returning Either have their unsafe counter-parts calling error. Most of them are either (error . pretty) id, which produces many similar functions at the call site, e.g.:

buildEpName = ...
unsafeBuildEpName = either (error . pretty) id . buildEpName

parseAddress = ...
unsafeParseAddress = either (error . pretty) id . parseAddress

To reduce duplication, we add an unsafe polymorphic converter from Either to Unsafe module:

unsafe :: (HasCallStack, Buildable a) => Either a b -> b
unsafe = either (error . pretty) id

As a result, all unsafeFName usages are replaced with unsafe . fName, e.g.

unsafeBuildEpName "a"
unsafe . buildEpName $ "a"

There are also Maybe converters/constructors which have an unsafe counter-parts and thus use non-trivial transformations like either (error $ errorMsg <> ... <> pretty arg) id. It's better to have them as Either ones too. So that fromHex, mkPos and mkChainId were refactored, as long as their usages.

In addition, it is also unsafeM function introduced in morley-prelude. It is pretty similar to unsafe, but throws a monadic exception via fail.

Related issue(s)

Resolves #711 (closed)

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