Add requesMTU for android

[wm-eisos]

Is your feature request related to a problem? Please describe.

Since android api 21, the device cam request MTU size using this function

public boolean requestMtu (int mtu)

i saw that you recently added the ability to read the mtu size so it would also be good to be able to request a size

[pwespi]

May I ask, what is your use case for this? Do you need a specific number for the MTU?

On Android, the plugin already automatically requests a large MTU. On iOS, this is done by the OS and there is no API to change the MTU, as far as I know.

[wm-eisos]

For me it would be useful since the app im writing is for developers to connect to a bluetooth wireless module so it would be nice to have tem control everything also i dont think it would be very hard to implement this and you are correct this is only available in android

[wm-eisos]

also it would be better for the peripheral to not always use a large mtu size to save power

[medfx]

On Android, the plugin already automatically requests a large MTU. On iOS, this is done by the OS and there is no API to change the MTU, as far as I know.

Would be great to init the plugin without it automatically requesting a large MTU.

[tiandongmao]

@pwespi We also need to control the MTU size for different BLE versions of phones and bluetooth devices.Thank you!

[HyperLife1119]

Any updates?

[peitschie]

Hi @HyperLife1119

A pull request implementing this would very much be welcome!