Simplify `TokenizerArgs.__post_init__` with Enum Tokenizer Type #2791

Job	Run time
test-readme-cpu / linux-job	4m 26s
test-readme-any / linux-job	4m 13s
test-advanced-any / linux-job	4m 13s
test-gguf-cpu / linux-job	4m 13s
test-advanced-cpu / linux-job	4m 13s
test-native-any / linux-job	4m 20s
test-multimodal-cpu / linux-job	4m 13s
test-quantization-any / linux-job	4m 13s
test-gguf-any / linux-job	4m 13s
test-evaluation-cpu / linux-job	4m 13s
test-evaluation-any / linux-job	4m 14s
test-quantization-cpu / linux-job	4m 15s
test-multimodal-any / linux-job	4m 13s
test-native-cpu / linux-job	4m 13s
test-distributed-cuda / linux-job	4m 15s
	1h 3m 40s

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