Add converter functions to produce path values from strings

[dsainati1]

Closes #1105

Description

This adds three converter functions to produce paths from strings:

fun PublicPath(_ identifier: string): PublicPath?
fun PrivatePath(_ identifier: string): PrivatePath?
fun StoragePath(_ identifier: string): StoragePath?

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• Targeted PR against master branch
• Linked to Github issue with discussion and accepted design OR link to spec that describes this work
• Code follows the standards mentioned here
• Updated relevant documentation
• Re-reviewed Files changed in the Github PR explorer
• Added appropriate labels

[turbolent]

👍

[codecov-commenter]

Codecov Report

Merging #1211 (c14c075) into master (2b9ff0d) will increase coverage by 0.23%.
The diff coverage is 89.02%.

@@            Coverage Diff             @@
##           master    #1211      +/-   ##
==========================================
+ Coverage   76.91%   77.14%   +0.23%     
==========================================
  Files         272      272              
  Lines       33887    33989     +102     
==========================================
+ Hits        26065    26222     +157     
+ Misses       6724     6703      -21     
+ Partials     1098     1064      -34     

Flag	Coverage Δ
unittests	77.14% <89.02%> (+0.23%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
runtime/interpreter/interpreter.go	87.92% <ø> (ø)
runtime/literal.go	86.36% <42.85%> (-1.88%)	⬇️
runtime/sema/errors.go	58.46% <50.00%> (-0.08%)	⬇️
runtime/sema/check_path_expression.go	85.18% <85.71%> (-3.71%)	⬇️
runtime/interpreter/value.go	82.32% <87.50%> (+1.49%)	⬆️
runtime/sema/type.go	87.76% <100.00%> (+0.22%)	⬆️
runtime/interpreter/conversion.go	95.12% <0.00%> (ø)
runtime/common/address.go	92.30% <0.00%> (+0.30%)	⬆️
runtime/interpreter/primitivestatictype.go	74.29% <0.00%> (+1.86%)	⬆️

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[turbolent]

Great work! 👏

[turbolent]

@dsainati1 There has been many requests from the community for this feature. Maybe we can backport it to v0.23 to get it out earlier?