Add fixed-length frames to FrameAccumulator helper

[timcanham]

F´ Version	v3.4.3
Affected Component	Svc/FrameAccumulator

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Feature Description

The Svc/FrameAccumulator supports a configurable frame pattern that includes a token, a size, and CRC checksums. This is a request to add an option whereby the frame size is known and fixed, so there is no size field.

Rationale

Support this type of frame.

[LeStarch]

Is this the right approach for this? The detectors were designed for a specific pattern, and other patterns were left up to users to implement. Do we need to support more patterns out of the box and do we need to simplify the template patterns that exist?