florisboard: Memory Error & No Auto Complete when binary flict is large ~ 6mb

Referring to this feature

I generated a binary flict using the dict-tools for en where size was 6.8 mb – about 3 times the default en binary flict. Size is larger due to more words and the highest dimension for n-grams used was 2. However when file is reduced to a small size, significantly fewer tokens, word-complete works fine.

Short description

Memory runs out when flict is too large

Steps to reproduce

1. Generate large flict > 6mb
2. Type an entire paragraph as quickly as possible
3. No auto-complete will show and keyboard will quickly crash in seconds
4. See error

Environment information

• FlorisBoard Version: current main branch, commit 38baac1af92fea80a86f5fdd8850bc677a27a3d2.
• Install Source: Github
• Device: Emulator Android Studio
• Android version, ROM: Android 11

~~~ 1614445172221.stacktrace ~~~

java.lang.OutOfMemoryError: OutOfMemoryError thrown while trying to throw an exception; no stack trace available
~~~ 1614445172167.stacktrace ~~~

java.lang.OutOfMemoryError: Failed to allocate a 80 byte allocation with 8 free bytes and 8B until OOM, target footprint 201326592, growth limit 201326592
	at java.util.Arrays.copyOf(Arrays.java:3257)
	at java.lang.AbstractStringBuilder.ensureCapacityInternal(AbstractStringBuilder.java:124)
	at java.lang.AbstractStringBuilder.append(AbstractStringBuilder.java:448)
	at java.lang.StringBuilder.append(StringBuilder.java:137)
	at dev.patrickgold.florisboard.ime.core.FlorisBoard.onUpdateSelection(FlorisBoard.kt:388)
	at android.inputmethodservice.InputMethodService$InputMethodSessionImpl.updateSelection(InputMethodService.java:906)
	at android.inputmethodservice.IInputMethodSessionWrapper.executeMessage(IInputMethodSessionWrapper.java:104)
	at com.android.internal.os.HandlerCaller$MyHandler.handleMessage(HandlerCaller.java:44)
	at android.os.Handler.dispatchMessage(Handler.java:106)
	at android.os.Looper.loop(Looper.java:223)
	at android.app.ActivityThread.main(ActivityThread.java:7656)
	at java.lang.reflect.Method.invoke(Native Method)
	at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:592)
	at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:947)

@patrickgold