fix: ensure leading blanks are always imported

[allanbowe]

Summary

Fixes two cases where leading blanks in character data were silently stripped during web service input/output, and relaxes an over-strict test assertion.

Changes

meta/mm_createwebservice.sas & server/ms_createwebservice.sas

1. JSON export now retains leading blanks
   Previously, non-special character values were exported using quote(cats(...)), which strips leading blanks. Replaced with '"'!!trim(...)!!'"' so leading blanks are preserved while trailing blanks are still trimmed.

2. Table imports now use $char informat
   The generated input statement used a plain $ informat, which strips leading blanks on import. A prxchange now rewrites :$ informats to :$char in the captured input statement, ensuring leading blanks in incoming data are retained.

tests/base/mp_jsonout.test.3.sas

• The assertion masks SYSINFO with band(&sysinfo, 64+128+4096+32768) (stored in sysinfo_masked, as SYSINFO is read-only) so only data-related differences fail the test:
  • 64 — base dataset has observation not in comparison
  • 128 — comparison dataset has observation not in base
  • 4096 — a value comparison was unequal
  • 32768 — number of observations differ

Verification

• mp_jsonout.test.3 now passes (JSON round trip identical for all special chars, including leading/trailing blank variants)
• sasjs lint passes clean

[allanbowe]

Test results:

ℹ Tests provided results: 125/125 (100%)
ℹ Tests that pass: 125/125 (100%)

[github-actions]

🎉 This PR is included in version 4.68.2 🎉

The release is available on:

• npm package (@latest dist-tag)
• GitHub release

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