feat: incremental gguf parser (#10822)

* incremental gguf parser
* gguf: update test to not rely on gguf on disc
* re-use existing create gguf
* read capabilities from gguf kv
* kv exists
* update tests
* s/doneFunc/successFunc/g
* new buffered reader

---------

Co-authored-by: Bruce MacDonald <brucewmacdonald@gmail.com>

fs/gguf/reader.go

@@ -0,0 +1,23 @@
+package gguf
+
+import (
+	"bufio"
+	"io"
+)
+
+type bufferedReader struct {
+	offset int64
+	*bufio.Reader
+}
+
+func newBufferedReader(rs io.ReadSeeker, size int) *bufferedReader {
+	return &bufferedReader{
+		Reader: bufio.NewReaderSize(rs, size),
+	}
+}
+
+func (rs *bufferedReader) Read(p []byte) (n int, err error) {
+	n, err = rs.Reader.Read(p)
+	rs.offset += int64(n)
+	return n, err
+}