WebConfigPropertyCollection: Escape curly braces2

[a-mcf]

Pull Request (PR) description

Fix issue #430 by doubling up curly braces enabling the use of URLRewrite variables.

This Pull Request (PR) fixes the following issues

• Fixes #430

Task list

• [X] Added an entry to the change log under the Unreleased section of the file CHANGELOG.md. Entry should say what was changed and how that affects users (if applicable), and reference the issue being resolved (if applicable).
• [ ] Resource documentation added/updated in README.md.
• [ ] Resource parameter descriptions added/updated in README.md, schema.mof and comment-based help.
• [ ] Comment-based help added/updated.
• [ ] Localization strings added/updated in all localization files as appropriate.
• [ ] Examples appropriately added/updated.
• [ ] Unit tests added/updated. See DSC Community Testing Guidelines.
• [ ] Integration tests added/updated (where possible). See DSC Community Testing Guidelines.
• [X] New/changed code adheres to DSC Community Style Guidelines.

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This change is 

[a-mcf]

This is a rework of https://github.com/dsccommunity/WebAdministrationDsc/pull/599 that had strange issues after the rebase was pushed. It's just one small helper function called when the filters are applied.

[codecov[bot]]

Codecov Report

Merging #612 (a190d48) into main (b2f3688) will decrease coverage by 2%. The diff coverage is 85%.

@@         Coverage Diff          @@
##           main   #612    +/-   ##
====================================
- Coverage    90%    88%    -3%     
====================================
  Files        18     15     -3     
  Lines      2773   1943   -830     
====================================
- Hits       2515   1712   -803     
+ Misses      258    231    -27     

Impacted Files	Coverage Δ
...urce/DSCResources/DSC_IisModule/DSC_IisModule.psm1	0% <0%> (ø)
...urces/DSC_WebSiteDefaults/DSC_WebSiteDefaults.psm1	0% <0%> (ø)
...rtyCollection/DSC_WebConfigPropertyCollection.psm1	97% <91%> (ø)
...IisFeatureDelegation/DSC_IisFeatureDelegation.psm1	100% <100%> (ø)
...ce/DSCResources/DSC_IisLogging/DSC_IisLogging.psm1	97% <100%> (ø)
...DSC_IisMimeTypeMapping/DSC_IisMimeTypeMapping.psm1	100% <100%> (ø)
.../DSCResources/DSC_SslSettings/DSC_SslSettings.psm1	81% <100%> (ø)
...ce/DSCResources/DSC_WebAppPool/DSC_WebAppPool.psm1	95% <100%> (ø)
...DSC_WebAppPoolDefaults/DSC_WebAppPoolDefaults.psm1	100% <100%> (ø)
...sources/DSC_WebApplication/DSC_WebApplication.psm1	91% <100%> (ø)
... and 5 more

[davetapley]

@johlju is there anyway I can help move this along?

[a-mcf]

I agree that you could remove the extra check for the data type since its already a string.

It's been a couple of years since I submitted the original PR, so I don't remember the details but I believe curly braces are supposed to be variables, and my intent was to make sure that variables with url rewrite were fixed and not to escape braces in all scenarios.

I think it checks for single vs double braces to avoid re-escaping something that's been escaped already and to reduce the odds of unintended issues. There may been a specific reason for it too, but I don't remember and I no longer have any IIS machines to test against.