Add tekken to the tokenize tool

[jackzhxng]

>> cmake -DTOKENIZERS_BUILD_TOOLS=ON -DSUPPORT_REGEX_LOOKAHEAD=ON . -Bbuild && cmake --build build -j9
>> ./build/examples/tokenize_tool/tokenize_tool tekken ~/hf/models--mistralai--Voxtral-Mini-3B-2507/snapshots/3060fe34b35ba5d44202ce9ff3c097642914f8f3/tekken.json "<s>[INST]Let's go swim at the beach!"

I tokenizers:regex.cpp:27] Registering override fallback regex
I tokenizers:tekken.cpp:88] Loading Tekken tokenizer from: /home/jackzhxng/hf/models--mistralai--Voxtral-Mini-3B-2507/snapshots/3060fe34b35ba5d44202ce9ff3c097642914f8f3/tekken.json
I tokenizers:tekken.cpp:112] Tekken version: v7, vocab_size: 131072, special_tokens: 1000
I tokenizers:tekken.cpp:123] Loading special tokens from JSON
I tokenizers:tekken.cpp:282] Initialized 1000 special tokens (1000 defined, 0 placeholders)
I tokenizers:tekken.cpp:140] Loading 130072 vocabulary tokens
I tokenizers:tekken.cpp:223] Processing 130072 vocabulary entries (limit: 130072)
I tokenizers:tekken.cpp:260] Built vocabulary with 130072 tokens
WARNING: All log messages before absl::InitializeLog() is called are written to STDERR
E0000 00:00:1755895132.712552 3548433 re2.cc:237] Error parsing '([^\r\n\p{L}\p{N}]?[\p{Lu}\p{Lt}\p{Lm}\p{Lo}\p{M}]*[\p{Ll}\p{Lm}\p{Lo}\p{M}]+|[^\r\n\p{L}\p{N}]?[\p{...': invalid perl operator: (?!
E tokenizers:re2_regex.cpp:22] Failed to compile regex: ([^\r\n\p{L}\p{N}]?[\p{Lu}\p{Lt}\p{Lm}\p{Lo}\p{M}]*[\p{Ll}\p{Lm}\p{Lo}\p{M}]+|[^\r\n\p{L}\p{N}]?[\p{Lu}\p{Lt}\p{Lm}\p{Lo}\p{M}]+[\p{Ll}\p{Lm}\p{Lo}\p{M}]*|\p{N}| ?[^\s\p{L}\p{N}]+[\r\n/]*|\s*[\r\n]+|\s+(?!\S)|\s+), error: invalid$
I tokenizers:regex_lookahead.cpp:27] Creating PCRE2 regex
I tokenizers:tekken.cpp:181] Tekken tokenizer loaded successfully. Vocab size: 131072, BOS: 1, EOS: 2
Vocab Size: 131072
BOS: 1
EOS: 2

PROMPT:
<s>[INST]Let's go swim at the beach!

Encoding...
[ 1 3 12598 1681 1974 64031 1513 1278 29397 1033 ]

Decoding...
<s>[INST]Let's go swim at the beach!