Add sym for OpAmp with 1..2 aux & feedback pins

[ubruhin]

SUMMARY

Adding symbols and components for OpAmps:

• OpAmp Single With Enable & Feedback
• OpAmp Single With Enable, Compensation & Feedback

DATASHEETS / REFERENCES

See LibrePCB-Libraries/Texas_Instruments.lplib#23

OPEN QUESTIONS / UNRESOLVED ISSUES

• Not sure if the feedback pin should go straight down (parallel to COMP), for a cleaner layout with the feedback resistor
• Realized that those two configurations are not really standard OpAmps, could not find any other OpAmp using those pins. Therefore struggling with the decision if those should really be added to this library or if the components should be made fully specific and moved to the manufacturer library 🙈

CHECKLIST

• I have read and followed the library conventions¹.
• For packages, I followed IPC7351C (see details in library conventions).
• For modified elements, I bumped their version number².
• I already used the new library elements in a design and verified their correctness (optional).
• I'm the copyright owner of the added content (i.e. the changes are made by myself, not copied/imported from somewhere else).
• I agree to publish all my changes under the CC0 Public Domain License³, allowing everyone to use and modify the content without any restrictions.

¹ Library Conventions: https://docs.librepcb.org/#libraryconventions
² Minor version bump if only metadata was modified (e.g. "0.1" -> "0.1.1"), major version bump if functional changes were made (e.g. "0.1" -> "0.2")
³ CC0 Public Domain License: https://en.wikipedia.org/wiki/CC0

[eto-]

I would probably set the FB pin vertical as in your comment.

This design clarify well that the 2 outputs are in parallel.

[eto-]

Components and symbols are fine

[ubruhin]

I would probably set the FB pin vertical as in your comment.

Agreed, thanks for the feedback (haha, feedback 🙈). I updated the symbols accordingly.

And regarding generic vs. specific: Since there don't seem to exist any other OpAmps of this kind, let's keep the components specific and in the TI library. This also gives the advantage that we can name the enable pin !PD like in the datasheet instead of the generic EN.