clip : improve projector naming

[ngxson]

I don't quite like the abstract naming like "resample", "merger", etc. It can be useful if one projector can be reused by various vision models. But unfortunately, that has hardly been the case.

The cumbersome bool has_*_projector pattern is also removed. The only variable being kept is has_llava_projector, because both MLP, MLP_NORM, LDP, LDPV2 are considered variants of llava projector.

Test result:

OK:   llama-mtmd-cli ggml-org/SmolVLM-500M-Instruct-GGUF:Q8_0
OK:   llama-mtmd-cli ggml-org/SmolVLM2-2.2B-Instruct-GGUF:Q4_K_M
OK:   llama-mtmd-cli ggml-org/SmolVLM2-500M-Video-Instruct-GGUF:Q8_0
OK:   llama-mtmd-cli ggml-org/gemma-3-4b-it-GGUF:Q4_K_M
OK:   llama-mtmd-cli guinmoon/MobileVLM-3B-GGUF:Q4_K_M
OK:   llama-mtmd-cli THUDM/glm-edge-v-5b-gguf:Q4_K_M
OK:   llama-mtmd-cli second-state/Llava-v1.5-7B-GGUF:Q2_K
OK:   llama-mtmd-cli cjpais/llava-1.6-mistral-7b-gguf:Q3_K
OK:   llama-mtmd-cli ibm-research/granite-vision-3.2-2b-GGUF:Q4_K_M
OK:   llama-mtmd-cli second-state/MiniCPM-Llama3-V-2_5-GGUF:Q2_K
OK:   llama-mtmd-cli openbmb/MiniCPM-V-2_6-gguf:Q2_K
OK:   llama-mtmd-cli openbmb/MiniCPM-o-2_6-gguf:Q4_0
OK:   llama-qwen2vl-cli bartowski/Qwen2-VL-2B-Instruct-GGUF:Q4_K_M
OK:   llama-mtmd-cli ggml-org/pixtral-12b-GGUF:Q4_K_M

[ngxson]

cc @HimariO , PROJECTOR_TYPE_RESAMPLER is renamed to PROJECTOR_TYPE_QWEN2VL

For qwen2.5, we can add PROJECTOR_TYPE_QWEN25VL. For code paths used by qwenvl, we will need to check ctx->proj_type == PROJECTOR_TYPE_QWEN2VL || ctx->proj_type == PROJECTOR_TYPE_QWEN25VL

But tbh the best way is to have a dedicated builder function for qwenvl, it makes the code much easier to read. I'll make a proposal in the next few days.