Update Ace to get latest a11y fixes

[gtritchie]

System details

RStudio Edition : Desktop and Server
RStudio Version : 2023.09.0-daily+397
OS Version      : any
R Version       : any

RStudio 2023.09 was upgraded to Ace 1.19; there have been several a11y improvements made to Ace since then, and we should consider upgrading Ace again soon to pick these up. From https://github.com/ajaxorg/ace/releases:

v1.20.0

Add gutter controls to keyboard accessibility mode (#5146) (5f2face)
Hide Ace content from assistive technologies to improve a11y by @akoreman in #5160

v1.23.0

signal gutterkeydown in keyboard accessibility mode (#5202) (538b18c)
Improve ARIA labelling fold controls (#5205) (dad5e6f)

v1.23.2

bug(autocomplete): fix a11y violations by @oykuyilmaz in #5241

v1.24.0

Allow more lines in hidden textarea to improve screen reader experience on Windows (#5225) (bccff5a)

• I have read the guide for submitting good bug reports.
• I have installed the latest version of RStudio, and confirmed that the issue still persists.
• If I am reporting an RStudio crash, I have included a diagnostics report.
• I have done my best to include a minimal, self-contained set of instructions for consistently reproducing the issue.

[jonvanausdeln]

Verified on 2023.12.0-daily+237
Windows 11, MacOS 12.6

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