args: refactor mlock/mmap/directio into load-mode (#20834)

args: refactor mlock/mmap/directio into load-mode (#20834)

* args: overhaul mmap/mlock/dio into single arg

Signed-off-by: Aaron Teo <redacted>
* docs: update docs with llama-gen-docs

Signed-off-by: Aaron Teo <redacted>
* chore: satisfy code quality

Signed-off-by: Aaron Teo <redacted>
* args: make the `+` sign an actual modifier now

Signed-off-by: Aaron Teo <redacted>
* chore: general code clean up + comments

Signed-off-by: Aaron Teo <redacted>
* arg: fix deprecated flags support

Signed-off-by: Aaron Teo <redacted>
* arg: quick sanity check

Signed-off-by: Aaron Teo <redacted>
* bench: sync llama-bench argument parsing

Signed-off-by: Aaron Teo <redacted>
* fix: bugfix variable behaviour + llama-bench lm column size

Signed-off-by: Aaron Teo <redacted>
* arg: inverse commands should do the opposite instead of doing nothing

Signed-off-by: Aaron Teo <redacted>
* bench: fix incorrect dash

Signed-off-by: Aaron Teo <redacted>
* bench: fix missing modifiers for deprecated flags

Signed-off-by: Aaron Teo <redacted>
* llama: switch back to thread_local

Signed-off-by: Aaron Teo <redacted>
* arg: switch back to single enum

Signed-off-by: Aaron Teo <redacted>
* docs: update arg docs

Signed-off-by: Aaron Teo <redacted>
* chore: fix missing `mlock` from llama_load_mode_from_str + cleanup llama-bench

Signed-off-by: Aaron Teo <redacted>
* llama: fix mlock not activating

Signed-off-by: Aaron Teo <redacted>
* arg: add deprecation warning when old and new flags are combined

Signed-off-by: Aaron Teo <redacted>
* arg: cont add comment for todo in the future

Signed-off-by: Aaron Teo <redacted>
* docs: sync with upstream

Signed-off-by: Aaron Teo <redacted>
* docs: re-sync with upstream again

Signed-off-by: Aaron Teo <redacted>
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Signed-off-by: Aaron Teo <redacted>