Add display impl to `Fragment` #170

Job	Run time
test (none, ubuntu-latest, bash)	51s
test (none, windows-latest, msys2 {0})	2m 10s
test (none, macos-latest, bash)	55s
test (std, ubuntu-latest, bash)	44s
test (std, windows-latest, msys2 {0})	2m 10s
test (std, macos-latest, bash)	57s
test (source-tracking, ubuntu-latest, bash)	54s
test (source-tracking, windows-latest, msys2 {0})	2m 13s
test (source-tracking, macos-latest, bash)	1m 11s
test (reporting, ubuntu-latest, bash)	45s
test (reporting, windows-latest, msys2 {0})	2m 6s
test (reporting, macos-latest, bash)	1m 2s
test (file_memmap, ubuntu-latest, bash)	48s
test (file_memmap, windows-latest, msys2 {0})	2m 6s
test (file_memmap, macos-latest, bash)	57s
test (ast-model, ubuntu-latest, bash)	49s
test (ast-model, windows-latest, msys2 {0})	2m 11s
test (ast-model, macos-latest, bash)	57s
test (lexer, ubuntu-latest, bash)	46s
test (lexer, windows-latest, msys2 {0})	2m 11s
test (lexer, macos-latest, bash)	55s
test (parser, ubuntu-latest, bash)	46s
test (parser, windows-latest, msys2 {0})	2m 12s
test (parser, macos-latest, bash)	1m 3s
test (wright_library_defaults, ubuntu-latest, bash)	51s
test (wright_library_defaults, windows-latest, msys2 {0})	2m 19s
test (wright_library_defaults, macos-latest, bash)	56s
test (wright_binary, ubuntu-latest, bash)	56s
test (wright_binary, windows-latest, msys2 {0})	2m 10s
test (wright_binary, macos-latest, bash)	59s
	39m 50s

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