Fix broken documentation in telephony and telecomm

Due to a bug in the build system, broken @see/@link references have not
failed to build for a while, so many errors have accumulated.

This is an attempt to patch up the telephony and telecomm docs. The
most common errors and fixes were:
- @link-ing IntDef constants from javadoc. IntDefs are not present
  in the docs, so rewrite those to natural english, or point to the
  constant prefixes
- Javadoc for public symbols referencing SystemApi symbols. Change those
  to @code instead of @link

There were various other fixes too, and I'm not sure they're all
perfect, but certainly an improvement over the brokenness we have
currently.

Bug: 303184203
Test: m docs
Change-Id: I5cefc72074ced29c0b046cf59deb7ee371e74bf0
diff --git a/telecomm/java/android/telecom/Call.java b/telecomm/java/android/telecom/Call.java
index 7d9b379..a7675d6 100644
--- a/telecomm/java/android/telecom/Call.java
+++ b/telecomm/java/android/telecom/Call.java
@@ -1894,7 +1894,7 @@
      * Tones are both played locally for the user to hear and sent to the network to be relayed
      * to the remote device.
      * <p>
-     * You must ensure that any call to {@link #playDtmfTone(char}) is followed by a matching
+     * You must ensure that any call to {@link #playDtmfTone(char)} is followed by a matching
      * call to {@link #stopDtmfTone()} and that each tone is stopped before a new one is started.
      * The play and stop commands are relayed to the underlying
      * {@link android.telecom.ConnectionService} as executed; implementations may not correctly