mtmd : support MiniCPM-V 4.6 (#22529)

mtmd : support MiniCPM-V 4.6 (#22529)

* Support MiniCPM-V 4.6 in new branch

Signed-off-by: tc-mb <redacted>
* fix code bug

Signed-off-by: tc-mb <redacted>
* fix pre-commit

Signed-off-by: tc-mb <redacted>
* fix convert

Signed-off-by: tc-mb <redacted>
* rename clip_graph_minicpmv4_6

Signed-off-by: tc-mb <redacted>
* use new TYPE_MINICPMV4_6

Signed-off-by: tc-mb <redacted>
* use build_attn to allow flash attention support

Signed-off-by: tc-mb <redacted>
* no use legacy code, restored here.

Signed-off-by: tc-mb <redacted>
* use the existing tensors name

Signed-off-by: tc-mb <redacted>
* unused ctx->model.hparams.minicpmv_version

Signed-off-by: tc-mb <redacted>
* use n_merge for slice alignment

Signed-off-by: tc-mb <redacted>
* borrow wa_layer_indexes for vit_merger insertion point

Signed-off-by: tc-mb <redacted>
* fix code style

Signed-off-by: tc-mb <redacted>
* Update convert_hf_to_gguf.py

Co-authored-by: Sigbjørn Skjæret <redacted>
* use filter_tensors and add model.vision_tower

Signed-off-by: tc-mb <redacted>
* fix chkhsh

Signed-off-by: tc-mb <redacted>
* fix type check

Signed-off-by: tc-mb <redacted>
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Signed-off-by: tc-mb <redacted>
Co-authored-by: Sigbjørn Skjæret <redacted>