Add Sabre plugin to whitelist the OP instance in the CORS headers

[julien-nc]

Add a Sabre plugin that changes the DAV response headers on some conditions. This is how the https://github.com/digital-blueprint/webapppassword app does it.

⚠️ We need nextcloud/server#35621 for this PR to work with requests to /public.php/webdav.
Otherwise it just works with requests to /remote.php/dav/files.

[github-actions]

JS Code Coverage

Coverage after merging enh/noid/sabre-plugin-cors into master will be

93.73%

Coverage Report

File	Stmts	Branches	Funcs	Lines	Uncovered Lines
src
adminSettings.js	0%	0%	0%	0%	1, 1, 10–19, 2, 20–25, 3–9
bootstrap.js	0%	0%	0%	0%	1, 1–7
dashboard.js	0%	0%	0%	0%	1, 1, 10–19, 2, 20–27, 3–9
fileActions.js	0%	0%	0%	0%	1, 1, 10–17, 2–9
personalSettings.js	0%	0%	0%	0%	1, 1, 10–19, 2, 20–25, 3–9
projectTab.js	0%	0%	0%	0%	1, 1, 10–19, 2, 20–29, 3, 30–39, 4, 40–49, 5, 50–59, 6, 60–66, 7–9
utils.js	57.45%	33.33%	50%	59.52%	10–14, 17–26, 6–9
src/components
AdminSettings.vue	99.21%	95.83%	82.35%	99.86%	1, 1, 1
OAuthConnectButton.vue	99.08%	80%	100%	100%	1
PersonalSettings.vue	98.88%	91.67%	83.33%	100%	1
src/components/admin
FieldValue.vue	95.56%	62.50%	100%	98.77%	1, 1, 1, 1
FormHeading.vue	98.98%	75%	100%	100%	1
TextInput.vue	98.50%	80%	87.50%	100%	1, 1, 1
src/components/icons
ClippyIcon.vue	93.18%	50%	50%	97.50%	1, 1
src/components/settings
CheckBox.vue	92.45%	80%	66.67%	97.62%	1, 1
SettingsTitle.vue	94.74%	50%	100%	97.14%	1, 1
src/components/tab
EmptyContent.vue	99.34%	90.91%	100%	100%	1
SearchInput.vue	99.56%	83.33%	100%	100%	1
WorkPackage.vue	99.01%	33.33%	100%	99.66%	1, 1, 1
src/utils
workpackageHelper.js	97.46%	96%	100%	97.75%	17–19
src/views
Dashboard.vue	98.20%	50%	50%	99.63%	1, 1, 1
ProjectsTab.vue	99.74%	92.31%	100%	100%	23

[github-actions]

PHP Code Coverage

Coverage after merging enh/noid/sabre-plugin-cors into master will be

63.89%

Coverage Report

File	Stmts	Branches	Funcs	Lines	Uncovered Lines
lib/AppInfo
Application.php	13.33%	100%	25%	11.54%	108, 112, 58–59, 62, 69, 71–73, 76–78, 83–86, 88, 92–97
lib/Controller
ConfigController.php	79.02%	100%	66.67%	79.85%	102, 119–120, 122, 124–126, 128, 134–135, 137, 326–329, 331–332, 335, 343–347, 358, 372–374
DirectDownloadController.php	0%	100%	0%	0%	36–38, 53–55, 57, 60–61
FilesController.php	73.68%	100%	100%	71.91%	168, 221–222, 267, 273–277, 281–282, 285, 287, 298–300, 303–304, 306–307, 311–314, 317
OpenProjectAPIController.php	84.92%	100%	78.57%	85.41%	136, 171, 188–189, 193, 197, 199–204, 206, 215–216, 219, 221, 223–226, 228–229, 234, 253, 278, 95
lib/Dashboard
OpenProjectWidget.php	0%	100%	0%	0%	101–102, 104–108, 116, 123–124, 126, 128–129, 131–132, 134, 137–138, 140–141, 143, 69–73, 80, 87, 94
lib/Exception
OpenprojectErrorException.php	100%	100%	100%	100%
OpenprojectResponseException.php	100%	100%	100%	100%
lib/Listener
LoadSidebarScript.php	0%	100%	0%	0%	100–101, 103–104, 106, 108, 65–70, 72–73, 75–76, 78–79, 85–86, 88, 90, 92–94, 96, 98
lib/Sabre
CorsPlugin.php	0%	100%	0%	0%	25, 33, 40–41, 44–46, 49–53, 55–57, 59
lib/Search
OpenProjectSearchProvider.php	0%	100%	0%	0%	102, 109–110, 113–116, 118–119, 123–125, 127–128, 130–131, 133–135, 138–139, 141–142, 146–147, 149–151, 157–158, 160, 169, 177–183, 192–197, 206, 71–75, 82, 89, 97, 99
OpenProjectSearchResultEntry.php	100%	100%	100%	100%
lib/Service
DirectDownloadService.php	88%	100%	100%	86.96%	65–66, 68
OauthService.php	0%	100%	0%	0%	37–38, 47–53, 55, 64–67, 78–85, 95–99
OpenProjectAPIService.php	87.17%	100%	90.91%	86.83%	112–116, 279–280, 282, 296–297, 306, 310, 331, 419–420, 427, 430–433, 435, 441, 445–447, 619, 690, 720–721, 723, 725–726
lib/Settings
Admin.php	0%	100%	0%	0%	32–34, 41–43, 46–50, 53, 58–59, 62, 64–65, 67, 71, 75
AdminSection.php	0%	100%	0%	0%	19–20, 29, 39, 48, 55
Personal.php	87.50%	100%	50%	92.86%	94, 98
PersonalSection.php	0%	100%	0%	0%	19–20, 29, 39, 48, 55

[individual-it]

I believe we can close this, as the direct upload was solved differently.
Or was there any other reason for this PR?