Add `cvector-generator` example (#7514)

Add `cvector-generator` example (#7514)

* add control-vector-generator

* calc diff

* add comments

* proof-of-concept stdlib implementation

Implements PCA and file writing using mostly standard libraries. The output is recognized as a functional control vector, but outputs gibberish.

* param parsing, refactor, comments

Added basic command-line parameters for outfile and one each positive/negative prompt.

Refactored some messy code in PCA computation and GGUF exporting.

Left a bunch of comments regarding further work needed.

* example template completions

Implements an example template set built from the positive/negative prompts like the control vector Python implementation.

* add multi prompts, multi-thread for PCA

* fix mem error

* add debugs

* fix matrix transpose multiplication

you have got to be kidding me

* preliminary template/multiprompt support

model is running out of context and that ought to be fixed (segfaulting) but other than that it looks goodish

* fix zero output & param parsing, functional templating

fixed a bug where the output file had no tensor data/was all zero

fixed a bug where single hyphen flags were not being correctly parsed

implements creation of templated prompts from input (still need to adapt based on model)

* fix square_diff matmul index range and CRLF->LF line endings

fixed a logic error where square_diff would not multiply all rows

fixed a formatting error where the provided completions.txt had CRLF line endings

* add command-line args for num threads, num completions file lines, always reload model

refactored a few things and did what the commit message says on the tin

* code aestheticization

* fix compiler warnings

* in-series multithreading for prompt embedding?

added commented-out code to attempt to start implementing mutlithreading for embedding in main

* remove unnecessary multithreading

* interim fix memory leak

* translated everything but PCA (I think)

* tentatively translate the rest

* fix ggml errors and make new ones

at least it compiles and runs

* fix cb_eval

* temporary commit while I move dev environments

it finally outputs a functioning control vector - "functioning" in the sense that it can be loaded and it clearly has the right idea, but makes the model incoherent

* update debug statements

* pre-tokenize so we can allocate correct memory to ctx_diffs_wrapped

* update comments

* (wip) refactor

* clean up PCA ggml implementation

* fix shape of v_diff_original

* add n_batch for pca

* working version

* remember to copy back the last_eigenvector

* fix n_completions

* bring back n_completions

* default n_pca_batch to 20

* fix macos build

* add to makefile all targets

* use ggml_format_name

* add readme

* fix .editorconfig

* use ggml_backend_tensor_copy

* attemp to fix compile problem on mac

* fix compile warn

* reuse allocr

* move param parser to common

* better error handling

* clean up a bit

* add print_usage

* shorten help msg

* beautify help msg

* escape prompt by default

* change compile target to llama-cvector-generator

* typo

* disable GPU for PCA

* code style

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Co-authored-by: Christian Zhou-Zheng <redacted>