Add option to specify root folder when searching for existing applets

[jdidion]

When building a workflow, the default search scope is the target folder only (specified by -folder).

Setting the -projectWideReuse flag instructs the compiler to look for existing applets/workflows in the entire target project before generating new ones. The search starts at the root folder (/) and is recursive. This can take a long time for large projects.

Add a new option, -executableReuseFolder, that specifies the folder where the search should start.

• This option is mutually exclusive with -projectWideReuse.
• The option's value is a project folder
  • The folder must start with /
  • The folder may have a trailing /
  • If the folder has a trailing /**, the search will be recursive, otherwise the search will not be recursive
• Resolution of ./ and ../ are not supported.
• If the specified folder does not exist, a warning is issued but compilation does not fail - the compiler just does not reuse any existing applets

There should be a test for each of these:

• -projectWideReuse is also specified: dxCompiler throws "can not specify both projectWideReuse and executableReuseFolder" error
• -executableReuseFolder /**: is the entire project, recursively. Equivalent to '-projectWideReuse`
• -executableReuseFolder /a/b/** : dxCompiler will search the folder /a/b/ recursively for executables to reuse
• -executableReuseFolder /a/b: dxCompiler will search the folder /a/b/non-recursively for executables to reuse
• -executableReuseFolder /a/b/: same as previous
• -executableReuseFolder /nonExistentFolder/ : dxCompiler will search emilt a warning and not reuse any executables
• -executableReuseFolder a/b: dxCompiler throws "executableReuseFolder argument must start with '/'" error
• -executableReuseFolder /a/../a: dxCompiler throws 'Folder name ".." is reserved' error (may happen during compilation, after the initial argument checking)
• -executableReuseFolder /a/./: same as previous