Speed up jnlp launch by 58%

[mgaffigan]

Speeds launch time by not requiring multiple round-trips for each plugin. Classpath with ballista remained identical. No obvious benefit to the historical design - presumed to be some Java Security Manager pipe dream.

Scenario	Before	After	% change
Cold cache, 100ms latency	8.9s	3.7s	↓58%
Warm cache, 100ms latency	5.8s	0.7s	↓87%

Mildly related: #197

[github-actions]

Test Results

  111 files  ±0    214 suites  ±0   6m 58s ⏱️ + 1m 6s
  651 tests  - 3    651 ✅  - 3  0 💤 ±0  0 ❌ ±0 
1 302 runs   - 6  1 302 ✅  - 6  0 💤 ±0  0 ❌ ±0 

Results for commit 77ad485. ± Comparison against base commit be1072d.

This pull request removes 3 tests.

com.mirth.connect.server.servlets.WebStartServletTest ‑ testDoGetExtension
com.mirth.connect.server.servlets.WebStartServletTest ‑ testDoGetExtensionModifiedURL
com.mirth.connect.server.servlets.WebStartServletTest ‑ testDoGetExtensionQueryParams

♻️ This comment has been updated with latest results.