Syntax folding should differentiate between regions and comment blocks

[glennsarti]

System Details

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• VS Code version: N/A
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Issue Description

While working on #1428 I thought of another possible issue with the syntax folding. Currently regions and comment blocks are detected as the same thing which will cause issues when comments are not separated by empty lines.

Given a script of

# Comment Block 1
# Comment Block 1
# Comment Block 1
#region
# Comment Block 2
# Comment Block 2
# Comment Block 2
$something = $true
#endregion

Expected Folding Regions

# Comment Block 1  --+-- Folding Line 1-3
# Comment Block 1    |
# Comment Block 1  --+
#region                                   --+-- Folding Line 4-9
# Comment Block 2  --+-- Folding Line 5-7   |
# Comment Block 2    |                      |
# Comment Block 2  --+                      |
$something = $true                          |
#endregion                                --+

Actual Folding regions

# Comment Block 1  --+-- Folding Line 1-7
# Comment Block 1    |
# Comment Block 1    |
#region              |  --+-- Folding Line 4-9
# Comment Block 2    |    |
# Comment Block 2    |    |
# Comment Block 2  --+    |
$something = $true        |
#endregion              --+