Change format of requests to show module sources

[StephenWeatherford]

Doing this because:

1. want easier way to change the title of a source document displayed in vscode
2. local cache file path that's currently in the URI is not needed
3. need to be able to request a specific file from the module source zip

Old format of the URI we send to vscode to display the source of a module (unencoded):
bicep-cache:{fullyQualifiedReference}#{localCacheFullPath}

Example:
bicep-cache:br:myregistry.azurecr.io/myrepo:v1#/Users/MyUserName/.bicep/br/registry.azurecr.io/myrepo/v1$/entrypoint.bicep

New format (unencoded):
bicep-extsrc:{title-to-display-for-document}?{fullyQualifiedReference}#{source-file-to-retrieve-relative-path}

Example:
bicep-extsrc:br:myregistry.azurecr.io/myrepo:main.bicep (v1)?br:myregistry.azurecr.io/myrepo:v1#main.bicep

No fragment in URI if just requesting the main.json file

Also changed other names, like:
BicepRegistryCacheRequestHandler -> BicepExternalSourceRequestHandler

Example of source document titles (exact format still being decided):

Microsoft Reviewers: Open in CodeFlow

[github-actions]

Test this change out locally with the following install scripts (Action run 6856854941)

VSCode

• Mac/Linux

  bash <(curl -Ls https://aka.ms/bicep/nightly-vsix.sh) --run-id 6856854941

• Windows

  iex "& { $(irm https://aka.ms/bicep/nightly-vsix.ps1) } -RunId 6856854941"

Azure CLI

• Mac/Linux

  bash <(curl -Ls https://aka.ms/bicep/nightly-cli.sh) --run-id 6856854941

• Windows

  iex "& { $(irm https://aka.ms/bicep/nightly-cli.ps1) } -RunId 6856854941"

[StephenWeatherford]

new code

[StephenWeatherford]

most of this file same as renamed file except name changes

[github-actions]

Test Results

     132 files  ±    0       132 suites  ±0   5h 13m 9s ⏱️ - 26m 37s
10 846 tests +163  10 846 ✔️ +163  0 💤 ±0  0 ❌ ±0 
52 307 runs  +680  52 307 ✔️ +680  0 💤 ±0  0 ❌ ±0 

Results for commit 009e1d7. ± Comparison against base commit b02de2d.

♻️ This comment has been updated with latest results.