WIP initial reshuffling of opts parsing API for #23009

[ejmg]

Note: This PR is not close to finished, I am pushing my code here for review and assistance.

This PR addresses the generation and parsing of command line options that are global versus specific, e.g. Gluten Embedded, by changing the from_cmdline_args() API by adding an opts argument that can be passed in by a specific embedder, separating the concerns and configurations from the global set of engine options.

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• ./mach build -d does not report any errors
• ./mach test-tidy does not report any errors
• These changes fix #23009(GitHub issue number if applicable)

• There are tests for these changes OR
• These changes do not require tests because ___

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This change is 

[highfive]

Heads up! This PR modifies the following files:

• @paulrouget: ports/servo/non_android_main.rs, ports/servo/Cargo.toml

[jdm]

This is basically what I expected!

[bors-servo]

☔ The latest upstream changes (presumably #22973) made this pull request unmergeable. Please resolve the merge conflicts.

[servo-wpt-sync]

Error syncing changes upstream. Logs saved in error-snapshot-1553276912875.

[jdm]

Looks like the rebase did not go as expected :(

[ejmg]

It really did not, and it's even more embarrassing that I thought I had fixed my rebase issues when I pushed this.

School things unexpectedly took priority this past week and a half, but I was planning on asking a friend on how to rebase and fix my branch's history this weekend. Am I roadblocking?

[jdm]

Not at all! I was just going through the queue of PRs that I'm supposed to review and making sure that I wasn't roadblocking.

[jdm]

For the record, the --angle flag is another one that only matters in ports/glutin, and was added in #22856.

[ejmg]

Alright, my friend @nucle0tides helped me undo the mess that was this branch. I'll be working and hopefully getting this done in the coming week or so!.

[ejmg]

@jdm I'm using the same pattern for all of these flags so far by making a global atomic bool to check/set from the embedder, including the new --angle. That work?

[jdm]

That still leaves the flag in components/config. For any flags that are only used in ports/ code, that's unnecessary.

[jdm]

To be more explicit - I would expect the angle opt parsing to cause a local use_angle variable to contain the result, and that variable can be passed to any code that previously used opts::angle(). That keeps embedding-specific details out of the rest of the engine.

[bors-servo]

☔ The latest upstream changes (presumably #23712) made this pull request unmergeable. Please resolve the merge conflicts.

[jdm]

Closing due to inactivity.