Retain original formatting for LSP messages, except in `echo` functionality.

[benjamindblock]

• Updates ale#lsp#response#ReadDiagnostics to always store the full, unaltered diagnostic message from the LSP in question. The current process is to replace all newline characters with whitespace (' '), which then leads to broken formatting when viewing complex output from an LSP with :ALEDetail and other commands.
• Updates ale#cursor#TruncatedEcho to replace newline characters with a space ' ' instead of an empty string '' to retain the previous style of formatting for echoed messages.

Related Issues:

• https://github.com/dense-analysis/ale/issues/2356
• https://github.com/dense-analysis/ale/issues/3068
• https://github.com/dense-analysis/ale/issues/2301

Screenshots

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