Support JSON output for XDR structures across all endpoints.

Add support for base64-encoded XDR fields to be returned as unpacked JSON.

# Details
The following endpoints have a new, optional request parameter, 
`xdrFormat?: ""|"base64"|"json"`:
  * `getTransaction`
  * `getTransactions`
  * `getLedgerEntry`
  * `getLedgerEntries`
  * `getEvents`
  * `sendTransaction`
  * `simulateTransaction`

When omitted, the behavior does not change and we encode fields as base64.

# New Response Fields
There are new field names for the JSONified versions of XDR structures. Any
field with an `Xdr` suffix (e.g., `resultXdr` in `getTransaction()`) will be
replaced with one that has a `Json` suffix (e.g., `resultJson`) that is a JSON
object verbosely and completely describing the XDR structure.

Certain XDR-encoded fields do not have an `Xdr` suffix, but those also have a
`*Json` equivalent and are listed below:

* _getEvents_: `topic` -> `topicJson`, `value` -> `valueJson`
* _getLedgerEntries_: `key` -> `keyJson`, `xdr` -> `dataJson`
* _getLedgerEntry_: `xdr` -> `entryJson`
* _simulateTransaction_: `transactionData`, `events`, `results.auth`,
  `restorePreamble.transactionData`, `stateChanges.key|before|after` all have a
  `Json` suffix, and `results.xdr` is now `results.returnValueJson`

Closes #124.

.github/workflows/codeql.yml

@@ -32,7 +32,7 @@ jobs:
           go-version: 1.22
       - run: rustup update
       - uses: stellar/actions/rust-cache@main
-      - run: make build-libpreflight
+      - run: make build-libs
 
       # Initializes the CodeQL tools for scanning.
       - name: Initialize CodeQL

.github/workflows/golang.yml

@@ -30,15 +30,11 @@ jobs:
       - name: Build libpreflight
         run: |
           rustup update
-          make build-libpreflight
+          make build-libs
 
       - name: Run golangci-lint
         uses: golangci/golangci-lint-action@a4f60bb28d35aeee14e6880718e0c85ff1882e64 # version v6.0.1
         with:
           version: v1.59.1 # this is the golangci-lint version
           github-token: ${{ secrets.GITHUB_TOKEN }}
           only-new-issues: true
-
-
-
-

.github/workflows/soroban-rpc.yml

@@ -31,7 +31,7 @@ jobs:
       - uses: ./.github/actions/setup-go
       - run: rustup update
       - uses: stellar/actions/rust-cache@main
-      - run: make build-libpreflight
+      - run: make build-libs
       - run: go test -race -timeout 25m ./cmd/soroban-rpc/...
 
   build:
@@ -79,7 +79,7 @@ jobs:
           rustup target add ${{ matrix.rust_target }}
           rustup update
       - uses: stellar/actions/rust-cache@main
-      - run: make build-libpreflight
+      - run: make build-libs
         env:
           CARGO_BUILD_TARGET: ${{ matrix.rust_target }}
 
@@ -168,7 +168,7 @@ jobs:
 
       - run: rustup update
       - uses: stellar/actions/rust-cache@main
-      - run: make build-libpreflight
+      - run: make build-libs
 
       - name: Run Soroban RPC Integration Tests
         run: |