server: inject date_string in llama 3.x template + fix date for firefunction v2

[ochafik]

Fixes #12729

• Now using the chat handler common_chat_params_init_llama_3_x & common_chat_params_init_functionary_v3_1_llama_3_1 even when there's no tools
• Pass "now" time to Minja & use it to define date_string for llama 3.x
• Added an e2e test (examples/server/tests/unit/test_template.py) to check the date appears in the prompt for llama 3.3 and firefunction v2

cc/ @CISC

[ggerganov]

@ochafik Good to merge.

[CISC]

@ochafik Not sure what's going on, could be related to changes in master?

FAILED unit/test_tool_call.py::test_completion_with_required_tool_tiny_fast[meta-llama-Llama-3.3-70B-Instruct-tool2-code] - AssertionError: Expected 1 tool call in {'role': 'assistant', 'content': '<|python_tag|>python.call(code=" her mommy. As she was done, she saw a big, scary. As she was done, she saw a big, scary. She was so happy and prouded all the peace. After, she couldn\'try again. Frace was so happy and prouded all the peach. Fraggagel and the peach. Fraggether, they were all the peach on their face. Once upon a time, there was a little girl named Lily. She loved to play outside in the park. One day, she went to the park with her mommy and daddy. They were very happy and had a big box. Lily was very happy and proud of herself for being so clean. When they got to the park, Lily saw a big box with a big box. She wanted to play with it, but she didn\'t want to go to the park. When she got to the park, she saw a big box. She was sad and didn\'t know what to do. As she was cleaning, she saw a big box. The boy was sad and didn\'t know what to do. Lily was sad and didn\'t know what to do. She didn\'t know what to do. After a while, she saw a big, scary box. The boy was sad and didn\'t know what to do. He didn\'t know what to do. He didn\'t know what to do. He didn\'t know w'}
assert (None)