Make displacements optional in mem refs

Description

Fixes a shortcoming in the AT&T assembly syntax that required complex memory references to always have a displacement.

Changes

• Allowed multiple sub-expressions within a parenthesized expression.

Additions

None.

Test and Review

To be filled in by the reviewers

• All of the methods are commented to expectation

• The methods are tested to satisfaction

• There are no unnecessary files present in the MR

• The continuous integration has no problems with the MR

• The MR is filled in as requested (including labels, milestones, and reviewers)

• The documentation is up-to-date

• All nullable parameters are marked as such

added typebug label

enabled an automatic merge when the pipeline for 6c537ec8 succeeds

merged

mentioned in commit 5465463d

mentioned in merge request !153 (merged)

unassigned @leverse